Remedial Herbology (NC-17, 3,000 words, Neville/Theodore), written by furiosity for hp_yule_balls.
It explores a very fascinating portion of canon--Neville's time at Hogwarts during seventh year. I love Neville a lot, and I thought his characterization here was wonderful. He's been facing up to life's challenges well, and is stronger and more capable, but his self-confidence still hasn't quite caught up with his abilities in all areas, and that's about exactly how I'd imagine him. I can see why other students might find him appealing, and why he still might not see himself in the same light. And I thought she did a great job with Nott's characrerization too--we don't get a lot of him in the books, but he matches up very well with what we do learn from canon, and is fleshed out enough in this story that he's gone from a character I'd really never had much interest in to one I'd like to get to know a lot better. Anyway, she does an awful lot here in 3,000 words (including a quite excellent first time in greenhouse two), so even if Neville/Theodore isn't your OTP (*pauses to laugh at the idea of Neville/Theodore being the OTP of anyone on my flist*), I say go read it!
Another of her yule_balls fics, Seven Minutes In Hell (NC-17, 5,900 words, Harry/Draco), is quite a fun read, which plays with some of fandom's most entertaining cliches--leather pants! truth or dare!--so you might want to check that one out too. :) Haven't read her third one yet, but am hoping to find time to check it out soon.