Everyone in any sort of fandom should check this out:
Not My Fandom Fest: We all joke about "fannish osmosis," and this comment ficathon is going to put that to the test. The object is to write a ficlet for a fandom you're not a part of based solely on what you've learned from your friends list and fandom at large.
I've contributed a few ficlets. You should too. :D
(My Sherlock one is totally
ariastar's fault.)