I'm hoping to start a furious trade on fic recommendations; I love H/C with Snape and am always on the lookout for more. I've got two to start things off with; one I just found and one I finished recently that was ... well, quite an amazingly written and nicely long fic.
1.
http://www.livejournal.com/community/snape_potter/647498.html - Untitled by
fuzzy_bumpkins. Rated PG, but the implications are there for a light HP/SS. Post HBP.
2.
"The Miseducation of Severus Snape" by Not Exactly Dickens. SB/SS, definitely NC-17, sometimes a bit beyond. Heed the warnings! Marauders-Era fic.