6 crossover fics and community pimpin'
If you haven't seen No True Pair yet, go check it out. It is full of awesome shiny things. ♥ There's allllll kinds of fun going on by all kinds of crazy talented people. If you're a fan of Aster or Coyo or Laylah, the tag links are awesomely handy that way!

Here's six of mine broken down by fandom, though I also highly recommend folks poke around the people I linked to above too (and the list of authors and artists that conveniently shows up on the right hand side of the pages). Nothing below is higher than PG-13 and should be worksafe, though I don't guarantee brainsafe or drinksafe. (Particularly not once the Really Special Mushrooms start doing the pelvic thrusts...)

FF7/FF12, Zack and Balthier: Fledgling
Discworld/FF7:AC, Granny Weatherwax and the Sephlings: Prudent
FF7/Fruits Basket (via Kingdom Hearts), Sephiroth and Tohru: The Edge of the Map
FF8/FF12, Laguna and Balthier: How the Story Goes
(pic) Fruits Basket/Bleach, Tohru and Yoruichi: That Pesky...
Bleach/Vagrant Story, Yoruichi and Sydney: Lost and Found

(crossposted various places)