Okay, it's really just 150...;D
They are in no special order and there may be the occasional repeat. Remember: using one of these cliches is OPTIONAL. If you think of one not included here you are welcome to use it. Also, feel free to write the cliche traditionally or turn it on its ear. All use is fair use. ;D
1) Forced bonding to defeat Voldemort/marriage law fics.
2) Glamour!Snape. Snape's hair isn't really greasy, it's because he works with potions all day/needs to be unattractive to children to maintain his cover.
3) Harry, accidentally or on purpose, finds a parallel reality where his parents are alive/where Neville is TBWL.
4) Harry travels back in time/uses the RoR and befriends Snape.
5) Cat!Harry or Cat!Snape.
6) Snape/Harry is wrongly accused of something/the WW is afraid he will become the next Dark Lord/has an incurable illness and needs help only the other can provide.
7) Snarry ensues via detention/Occlumency lessons/private tutoring.
8) Super-powerful Harry.
10) Newly divorced/widowed Harry discovers Snape is still alive but in hiding.
11) Snape is Draco's/Albus Severus' Godfather.
12) Someone plays matchmaker for Snape and Harry.
13) Love potions/aphrodisiac.
14) Sex magic/rituals/Beltane.
15) Dumbledore orders them into hiding and Snape secretly trains Harry.
16) Deeply depressed/suicidal!Harry only reacts to/overcomes his problems with the help of Snape.
17) De-aged!Snape is sorted into Gryffindor.
18) Harry is sortrd into Slytherin.
19) A potions accident/Harry coming of age sparks off a dormant creature inheritance. Harry and Severus are mates.
20) Harry receives a letter magically on his 16th birthday from Lily telling him of a previously unknown creature/founders inheritance/marriage to Snape.
21) Harry is superpowerful and Severus is his mate/slave/bonded.
22) Snape rescues Harry from Dursley abuse and they enter into a bond (apprenticeship, Erastes/Eronemos, guardianship) to keep him protected. They fall in love or are soulmates.
23) Slave!Harry or slave!Snape, property of the other or rescued from someone else.
24) Harry wants mpreg and needs Severus to make the potion.
25) Severus wants his due. Hate!sex or revenge!sex.
26) Master/slave or Dom/sub where Harry needs to be controlled/punished/taught.
27) Simple seduction -- one simply must have the other and makes plans to get them.
28) Evil!Harry enslaves/brings Snape under his thrall.
29) School trip in forest/canyon/mountains/overseas. Harry (teacher or student) and Snape got lost/spend time together.
30) Snape/Harry stuck in Animagus/other transfigured form, stuck with the other as caretaker.
31) Harry has to stay at Hogwarts over the summer.
32) Harry becomes next Dark Lord, with Severus as second-in-command.
33) Severus and Harry stuck in a safe house.
34) Snape is Harry's father.
35) Harry is hurt/has an illness only Snape's potions/dark magic can cure.
36) Snape and Harry are together then one loses his memory and the other has to prove why they're in love.
37) Snape - Slytherin Sex God.
38) Dark!Veela Snape.
39) Pureblood Snape trains Harry in secret at Snape Manor.
40) Secretly wealthy!Snape.
41) Pro-Quidditch player/DADA instructor/Auror/Healer Harry
42) Potions accident/misspoken spell--Snarry are bonded and Harry pregnant.
43) Truth serums/potions revealing hidden feelings.
44) "It's just sex/a one-off!" turning into True Love.
45) Virgin Harry/Snape.
46) Snape needs Harry's parseltongue abilities.
47) Snape is accused of molesting a student, Harry comes to his defense.
48) Snape and/or Harry's Animgagus form is something really unexpected.
49) Severus is the only one that can brew the potion that Harry or one of widow!Harry's kids so desperately needs.
50) Harry is very powerful. Snape is drawn to power/ Harry needs Snape to control his magic.
51) Snape and Harry are madly in UST (via training/potions accident/etc) but Snape insists on waiting til Harry is 17/out of school/etc.
52) Snape teaches sex education classes at Hogwarts.
53) Abused and badly injured by the Dursleys!Harry is taken in and cared for by a reluctant Snape.
55) Sirius discovers Snape is with Harry and Remus must calm him down.
56) Snape and Harry become close via the internet or misdirected mail. Neither knows who the other one is.
57) Detention fics that appear to be chan, but are polyjuiced adult roleplay.
58) Snape's powers are shackled after the war & he's publicly attacked; Harry sympathizes & protects him.
59) Harry & Snape are imprisoned together & they
60) Broken!Crazy!Harry after the war; Snape's the only one who can control him.
61) Snape keeps Harry as a slave/pet, doesn't tell him what's going on in the world.
62) One of them has to resort to prostitution after the war; the other becomes his best/only client.
63) AU where Snape rescues Harry from the Dursleys before Book 1.
64) The war destroys Harry's and/or Snape's magic.
65) Harry is embarrassed to realize he's got the hots for Snape.
66) Snape is appalled to realize he's got the hots for a student, and more appalled that it's Harry.
67) Snape is secretly giving info to OotP; Harry's his contact.
68) Both are anonymous & meet up for sex; figure out who the other one is and thinks, "I can never tell him who I am."
69) Harry has to marry (or at least have sex with) Snape to get protection from Voldemort's magic.
70) Homosexuals are hated in the wizarding world; their love is secret/forbidden.
71) Post-war: Snape is Headmaster/teaches potions; Harry is DADA professor.
72) Voldemort demands that Snape court Harry.
73) Potions accident makes Harry reveal his true feelings.
74) Harry bribes Snape with sex for info about Lily.
75) Their patronuses mean they're in love/are compatible (and Harry figures it out).
76) Harry comes out only to have his friends turn their backs on him and Snape is the only one who still acts the same.
77) Disabled Harry/Snape (blind/deaf/lost limb/something else).
78) A Potions Accident forces Harry to strip off and reveal his Quidditch-toned thighs while gazing into Snape's onyx eyes...
79) A Game of Truth or Dare, an Occlumency lesson, or [insert cliche of your choice] reveals Harry/Snape's true feelings for Snape/Harry...
80) Harry's parents are alive. They went into hiding leaving Harry to fend for himself then return to find Harry married to Snape.
81) Ginny/someone tries a love/soulmate spell on Harry and instead of her it bonds Harry to Snape.
82) Harry thinks that Severus is only "nice"/interested in him because he is Lily's child.
83) Severus is only strong on the outside, but inside he feels undeserving/ugly/whatever. Harry needs to teach him how desirable and wonderful in his own way he is.
84) Post-DH, Harry thinks Snape is dead, mourns him, only to find out he's hiding out in the Muggle world.
85) Harry becomes obsessed with Snape after he dies, his relationship with Ginny is on the rocks and he belligerently goes off to find himself...and finds Snape.
86) 40 Year Old Virgin!Snape.
87) Auror Harry must find or convince Snape to help him with a case and get over their old feelings of animosity.
88) Snape is really Harry's father but they don't learn that until after they've started a relationship.
89) Happy nanipulation by Dumbledore Snarry (ie forced to live together until the reading of Albus' will...or some such scheme that Albus had planned with a twinkle in his blue eyes because he just knows "those boys belong together").
90) Snarry as revenge against James or still in love with Lily.
91) Harry's been spelled/potioned into loving Ginny, but has secretly been in love/gay (For Snape!) forever.
92) Snape sees/believes Harry is with Ginny or Hermione and thinks Harry could never love him so never says/does anything until some crucial moment when they get forced together for something.
93) Snape catches Harry masturbating in the Quidditch changing rooms/showers.
94) Harry and Snape are in a discreet relationship. Falling out occurs over misunderstanding in a situation where they can't talk openly. Both feel betrayed/abandoned/that they are the noble one. Much angst ensues. Readers scream at the 2 idiots to DISCUSS IT DAMMIT.
95) Harry is imprisoned/captured and Snape is his jailer with ambiguous loyalties.
96) There's a new prophecy and it requires Snape and Harry to
97) Snape and Harry each see themselves as people who have done horrible things and are thus unforgivable, unredeemable and unworthy of any or much human contact or affection from others. Through contact and sharing experiences with the other, they begin to each find some measure of redemption in the other's eyes, and each begins to be able to live with himself.
98) After the events in DH, Snape is in a coma/near death. Harry goes into his mind in an attempt to get him out and back to the realm of the living and waking. Harry ends up rewriting Snape's memories from childhood including himself in them (sometimes as replacement for Lily).
99) Harry has a crush on the half-blood prince. They enter into some form of correspondence.
100) Snape and Harry have some kind of accident through sharing magics that ends them up with an unstable bond. This has adverse affects on one or both of them. They require contact (and perhaps a lessening of animosity)for the bond to stabilise.
101) Post-Hogwarts, one of them agrees to pose as the love interest of the other to deter some unwanted suitor.
102) One of them gets amnesia and forgets their entire relationship; the other must woo him back.
103) Dumbledore locks Harry and Snape up together somewhere in a final desperate attempt to make them get along, and they end up getting along, um, rather well.
104) Post-DH, Harry still has Snape's memories and decides he must return them.
105) Post-war, Snape opens an apothecary and Harry is his customer/employee/benefactor.
106) Future dystopia - the Ministry controls magic/Slytherins for fear of a future Dark Lord.
107) Future dystopia - the Muggle government represses magic.
108) Post-War, Snape and Harry convalesce together.
109) Harry falls in love with Snape's portrait/ghost.
110) Harry didn't know the wizarding world is homophobic, and Snape educates him.
111) Harry didn't know the wizarding world has no problem with gay relationships, and Snape educates him.
112) They encounter each other in a gay bar/club.
113) One is left with the care of a child and the other helps.
114) The Dark Mark will kill Snape when Voldemort dies, and Harry must save him.
115) A Potions accident, spell, or magical artifact leaves one or the other speaking the truth/telepathic/giving away their attraction.
116) Godric Gryffindor and Salazar Slytherin's love shows them that their houses don't mean they're incompatible
117) Harry and Snape are called upon to save the world again.
118) Snape, though attracted to Harry, sends him away for more life experience, 'for his own good'. And of course Harry comes back....
119) Snape is ordered to rape a captured Harry before Voldemort/the Death Eaters.
120) Harry, believing he is adressing the Half-Blood Prince, inadvertently communicates with Professor Snape using dream-inducing potions/the spelled pages of Advanced Potion-Making/owl-post.
121) Snape tutors/mentors Harry's children (particularly Albus Severus) and Harry becomes jealous/alarmed/etc. After a series of visits to Hogwarts/angry letters/heated misunderstandings, Snarry ensues.
122) Harry becomes so obsessed with Snape's pensieve memories that he either discovers a hidden memory/wank fantasy involving himself or is able to interact with memory!Snape.
123) Body-swap: Snape must endure Gryffindor tower while Harry must play Snape's double spying role.
124) Schoolboy!Harry and Snape are secretly involved. Snape is severely injured in a DE meeting, Harry give away the relationship by his reaction/panic.
125) Snape is in the afterlife, but is sent back to the world of the living by Dumbledore/Lily/some higher power either in order to take care of Harry or because Harry intercedes with Death on his behalf.
126) Harry raises Snape from the dead/a ghost-like state using the resurrection stone/an arcane and dangerous ritual.
127) Snape is alive after the final battle, but the loss of his memories has triggered amnesia/shell-shock/de-aging. Sometimes he can be restored by the return of his memories alone; at other times, Harry must use Occlumency in a last-ditch effort to rebuild Snape's psyche. Often, Harry thereby ends up taking Lily's place in Snape's mind.
128) Harry sends his owl to no-one in particular and ends up corresponding with Snape, who at first keeps his own identity a secret.
129) Harry needs Snape to brew Wolfsbane/a cure for Lycanthropy for Remus, Bill or Teddy.
130) Alcoholic Harry or Snape and the only person that can help them is the other.
131) Undercover Auror/Unspeakable Snape partnered with Harry after the war
132) Both have lost everyone they cared about and through snarky conversations and unexpected meetings they cope together.
133) Harry the DE-orgy-victim. Features Snape as the reluctant, guilt-ridden yet aroused participant and follows up with the falling in love with ones - reluctant, usually - rapist trope. In dark variations Snape gleefully participates or has engineered the situation even, Obliviates and repeat performances of clueless!Harry may ensue.
134) Harry is sent to another school by Dumbledore and Snape is sent along as bodyguard/baby sitter.
135) Snape angsting about being not good and noble enough for pure, warm-hearted, hero Harry.
136) Snape actually had the hots for James.
137) Snape and Harry are comrades in arms or subordinate/commander, spy and handler etc and fall for each other as fellow warriors.
138) Either Snape or Harry is under polyjuice potion because of what they are trying to do/or are hiding from the unforgiving Ministry/numerous fans/not-quite well-wishers. Snarry ensues.
139) Snape or Harry are hiding a secret fetish/desire/hobby (may be just a yearning or actually doing it). The other finds out.
140) Snape and Harry stuck in a safe house, during a snow storm. No power and heating charms don't work/aren't safe to use; must use body heat to stay warm!
141) One has to court the other, in traditional wizarding ways. Either because they are infatuated with the other, or because Albus insists on it to prevent some alternative.
142) Courting again, but where it is done in secret and the recipient is puzzling over who is sending them all these gifts/love letters etc.
143) They get locked in a room and cannot get out until they get over their differences and have sex.
144) Where they "meet" by exchanging letters (such as thru a newspaper ad) and they get along wonderfully.... and then they arrange to meet in person....
145) Classic tales retold with a Snarry twist.
146) Harry or Snape is impotent. The other cures him.
147) Harry worries Snape could never be interested in him/he's just a substitute for his mother.
148) Harry's about to graduate/just graduated and tells Snape that he's completely in love with him (and has been for forever!!!) and Snape gets really mad and accuses Harry of playing a prank on him.
149) Harry's been dosed with some sort of aphrodisiac due to a potions mishap/spell/deliberate sabotage and fortunately Snape is on-hand to help him work through the effects.
150) Snape and Harry enter 'our' world and switch places with Dan and Alan. Or they critique the books/movies.