Speaking of crossovers, I have two ideas that I think could be interesting. Who knows? Maybe I'll actually write something worthwhile next year. :-)
1) Harry moves to Sunnydale fic. Now, before you write this off, let me explain! It would go AU from the beginning of OotP. At his Misuse of Underage Magic hearing, Harry is expelled from Hogwarts. Hermione puts him in touch with her parents; after all, what does the Ministry of Magic care what Muggles do? They help him get on his feet in the Muggle world, and later act as go-between for the Hogwarts crew. Harry (and Sirius) leave Britain, since Harry can't really protect himself without a wand, and neither he nor Sirius want to spend the rest of their lives locked up in Grimmauld Place. They end up in Sunnydale, where Harry meets Willow, since he really needs a tutor to help him catch up with his Muggle schooling. And, of course, they all meet Buffy later and crazy things happen.
Meanwhile, back at
That's all I have for right now. If anyone has any ideas, I'll be glad to listen.
2) This one's a bit more angsty than the first. It's a post-DH (but pre-epilogue) Hermione fic. After the war, Hermione's feeling a bit at sea. Her friends are planning on becoming Aurors, but Hermione's tired of fighting. She's just restored her parents' memories, and they, understandably, are furious. She decides to spend some time away from Britain and just wander for a bit.
Since we were finally given official dates in DH, we know that without tweaking the timeline, the end of DH (not including the epilogue) corresponds to the end of season 2 of BtVS. Well, a bit later; I believe that the "final battle" happened in June. Figure a few weeks for Hermione to make arrangements and finish her business in Australia, and she could be in the States by end of July/beginning of August. Hermione ends up in Sunnydale before Buffy returns from LA. She comes across a group of teenagers fighting vampires, and, since she's Hermione (and one who's just been through a war), she helps. Unlike the first fic, which is more political and action, this fic is more about Hermione healing from the war and coming to terms with her actions and her losses. I'm not sure if I'll stay with canon 'ships or not; probably not, since I really can't stand Ron/Hermione, but I'll figure that out if I decide to write it.