The Other Side of Darkness by Abby
SS/HG, post-war AU. Hermione (now a Ministry researcher) must ask a certain snarky Potions Master for help if there's going to be any hope of curing an Auror rendered comatose by a mysterious Potion. But Snape seems to know more than he lets on.... Is he to be trusted? And what is Hermione to do when her feelings about her former professor start to change? Excellent, surprising and thoroughly satisfying adventure. Complete (and now with sequel!)
The Phantom of Hogwarts by Good_Witch (at Ashwinder, so you'll need to login; Petulant Poetess' version seems a few chapters behind)
SS/HG, AU. Thanks to a new Ministry Decree, Hogwarts finds itself putting on - the Phantom of the Opera? And the cast list might surprise you. Hermione and Severus must deal with their new situation, and more importantly their feelings, while trying to lead Hogwarts to victory in the new tri-school musical competition. Very good, and probably the best take on this situation (Hogwarts meets PotO) that I've seen. Well-written, but LONG. WIP.