I hit the halfway mark on Thursday, and I've been managing to get somewhere between (the required) 1667 and 2000-odd words a day. I've been writing a lot on my old IBM Thinkpad 380, which is perfectly fine for word processing and has the added advantage of not having a lot of extra things on it (it's harder to get on the 'Net with it, for example), so I don't have as many distractions.
My story is about monster hunters in a fantasy analogue of Elizabethan England. I guess you could call it a cross between Buffy The Vampire Slayer and Elizabeth. A fair amount of inspiration for it came from Mercedes Lackey's books, Ill-Met By Moonlight and This Scepter'd Isle; I replaced the elves with slayers and sorcerers, and went from there.
If you'd like to be put on my NaNo filter, where I post word counts, excerpts and random observations about NaNo, leave a comment here and I'll add you to the filter on writersgrove. Longtime friends who are already on the filter are all set; you don't need to reply. :)