The Kindness of Women by deslea (R; one shot)
Snape/Lily, Snape/Tonks, Snape/Narcissa. The kindnesses of women, the search for identity, and the ways in which they collide. This story is unique in every way. It's unusual to find Snape paired with Tonks, and these two get the most "on screen" time in the story, although Lily is Severus's major unrequited love. This story oozes desperation and a burning desire to make the things we know about ourselves, our world, and our families, intelligible. Tonks and Snape are both especially well-written, showing us a side of the Order and its members that we aren't privy to in JKR's world.
To Weave Cold Starlight by shyfoxling (PG; one shot)
Snape/Lily, James/Lily. Severus wants to make Lily a special gift of something she saw in a book in the library, but doesn't get the chance to until after they're both dead. It turns out to have surprising properties. This story is definitely out of the ordinary in the realm of SS/LE. It includes a special magical artifact, a long chat in the afterlife, and a Severus who is intelligent, inquisitive, and dedicated.
Phantom Cruciatis by lizbee (PG-13; one shot)
Snapecentric Gen. He has eaten death, darkness and oblivion, and now there's only memory and madness. This summary kind of gives you an example of how the fic is written. Severus is tortured by Voldemort and the author does an expert job in illustrating the disintegration of his sanity. The end is hopeful, but if you're looking for something with a ethereal, disjointed feel to it then you should give this a try.
Piss Tank by cathedralcarver (PG-13; one shot)
Snape/Lily. Sometimes a storm comes on quickly, and when it’s over, everything has changed. The author of this piece gives us a really compelling, sympathetic characterization of Severus and his feelings for Lily. We get to see his family history, which lends itself well to the concept of a moody, disenchanted Severus. This is definitely a romance, and the development between Snape and Lily is both satisfying and beautiful to read. cathedralcarver has a way with prose that's always striking and poetic.
Sugar Quills by melisande88 (R; one shot)
Snape/Hermione. Snape favors three ways to get what he wants: manipulation, coercion, and addiction. Okay, this story is much darker than the other recs featured here. It's written from Hermione's perspective and the author does a masterful job of holding the answer to the mystery until the very end. The final conclusion is powerful and unnerving and it will make you literally shiver.
Here is the Deepest Secret that Nobody Knows by cathedralcarver (PG-13; one shot)
Snape/Lily, Remus/Snape, Lily/James. I carry your heart. I carry it in my heart. This fic is full of great lines that just reach out to you with emotion. We follow Severus, Lily, and Remus during their time at Hogwarts, watching as various love triangles are created. The author makes great use of poetry in her writing, gathering inspiration from e.e. cummings and applying it beautifully.
Mind Games by arsenicjade (NC-17; one piece but definitely on the longer side)
Harry/Snape. Occlumency lessons are revealing things. I was attracted to this because of the insightful, biting depths that AJ goes to in writing this. The majority of the fic isn't centered on the pairing, instead leading us through a long development between Harry and Severus through occlumency training. If this branch of magic is interesting to you I'd give this fic a try. Jade portrays both characters in a flawed, dynamic, layered form of storytelling. She draws non-cliched parallels between Harry and Voldemort while showing us the slow, natural progression between Harry and Snape from student and teacher to friends to lovers. Even if you don't like slash I'd encourage you to read this for the quality of writing.
A Line So Fine by shyfoxling (NC-17; one shot)
Snape/James. According to Sirius, Lily didn't know too much about James continuing to hex Severus during their seventh year. Well, that's not all she didn't know about, and apparently James has a fetish for a certain spell of Severus's creation... This piece is so well characterized that every line delivers a punch. The author really captures the characters and uses them to create a beautifully executed conflict full of raw, sexual tension. This is one of the most impressive pieces I've read in a good while.
The Three Brothers by ALD-Artworks G
Snape, Harry, Voldemort. A great gen piece with attention to artistic detail.
Snape by dvervzimu G
Gen. A portrait of Severus at a younger age. This author really captures the spirit of his character, especially in the hair and expression.
Beautiful Lily by Gregory-of-Yardale PG
Snape/Lily. This piece has a kind of sadness to it that radiates from Lily's eyes and Severus's body language. The colors are soft but vivid, with little ominous details like the trace of blood on Snape's hands.