Just wanted to rec this Browncoat Green Eyes, a marvelous Harry Potter/Firefly crossover. Kept me happily engrossed for many hours - for once I didn't read it all in one or two massive reading sessions, but carefully resisted myself to only several chapters at a time and made it last. Lovely stuff.
Annoyingly, it looks like it's getting to that time of year when I have to start putting the heating on again. *pout*