This post will focus on Harry Potter, with a heavy leaning towards the Severus Snape/Hermione Granger pairing.
Note: This list will include smut and crack.
Snamione/ Snape x Hermione:
Camerado Hermione seeks knowledge from a reluctant Snape in order to help the War effort. What she receives is more than either of them expected. Set beginning in Hermione's sixth year, continuing into a slightly AU post-DH era
Achluophobia is simply one of the most beautiful pieces of writing I've ever read. It flashes between timelines a lot, and is a little hard to follow in a way, but is worth the read.
Dark Angel It all started with the cloaked figure in the window. From there Hermione learns there is no black and white in a war...only shades of grey and a dark angel that comes to her rescue...or does he?
Against All Better Judgement and its sequel Throwing Caution to the Wind are cute Snamione fluff.
I Beg to Differ is Snamione smut with an interesting premise.
In Your Dreams Circumventing a prophecy is not that easy...
Phoenix Song, or Hermione Granger and the Half Blood Prince is the the first in a fanfiction trilogy.
The Professor's Discretion The only thing keeping Hermione out of trouble and Harry Potter alive is... the Professor's Discretion.
Professor Snape Bangs Again This is the smuttiest smut on this list, but I felt it worth including because Snape's personality is very canonish despite the sex.
Second Time Around When an accident in Potions class leaves Severus Snape's adult mind trapped inside his sixteen year old body he fears that his life will be as unbearable as it was when he was first in his teens. Help soon comes however from an unlikely source.
Snape mentors Harry:
The Guiltless When Harry appears at the Welcoming Feast wearing a glamor only Snape notices, Snape decides to find out what the glamor is hiding. His investigation leads to a number of shocking revelations about both Harry and himself.
One More Hour As Harry enters the final stages of a plan to kill himself someone races against the clock to find him. Can they find and pull Harry back from the edge?
Harry Potter and the Severus Snape Parody After reading so many stories about where Severus Snape is somehow Harry’s father, I have decided to write a parody about them.
Once Upon a Freakin Time Crack fic. The Death Eaters attempt to do bad things, but mostly just do things badly.
The Day Draco Malfoy Lost Something Very Important Draco wasn't supposed to go into that room, he knew that. But, like a child drawn to a shiny object, he'd been unable to resist. He stretched his legs out straight and pulled back the waistband of his pants to peek inside. Still gone. This was bad.
Missing from this list because I couldn't find the darn stories:
1. An amazing fic about Hermione going into a coma after she jumps in front of a spell intended for Snape during the final battle. Severus starts visiting her regularly at St. Mungo's (where Poppy's Sister works), but a few chapters in, its discovered that Snape can communicate with her through Occlumency. She's then taken to Hogwarts while everyone tries to figure out how to break the spell. What makes this story amazing is the description of Hermione's mental deterioration, and the mind-screwing plot twist near the end.
2. A severitus/ Snape mentors Harry fic where Harry spends a summer (after GoF?) helping Snape restore his family home. There's an OC caretaker character with a crush on Snape who's awful to Harry.
3. The fic where McGonagall 'accidentally' loses a mirror that reveals your soulmate. This mirror does a tour of Hogwarts, and a dance is organised in honour of it, to help the soulmates get together. This is a Snamione fic, but what I love most about it is the relationship between Hermione and Draco.
4. A crack fic where Harry replaces the study group's notes with a romance novel parody without realising that Severus asked to see the notes too. This had something to do with a challenge involving Snape writing romance novels, but what makes it great is Harry's summary of a romance and the parody he pens.
If any wandering Internet user who stumbles across this list knows which stories I'm talking about, please, PLEASE, drop me a link in the comments.