You can apply for my friend Neo-Wolf's hack.(yeah, I was the one who informed him about ya! :P)
He really needs spriters. You can apply at his GMK thread. (link is in his signature)
Or you can just search around the ROM hacking forums to find some team who needs your help.
(But note that they always ask for proof. Make a custom trainer sprite and show them as a proof of your awesome skills when ya apply.)
All the best! :)