...For what version of RPG Maker? And what kinds of sprites? Battle charsets (RM2k3), Battlers (RMXP), Charsets (RM2k3, RMXP), Facesets (RM2k3), Weaponsets (RM2k3), pretty much every resource that's not music is a sprite of some sort, and each is pretty much unique to the version of RPG Maker (with a few exceptions).

Because I have no idea what you're looking for, I'll just throw out the standard links:

www.phylomortis.com
www.lrpgm.com

There's lots of random resources on those sites.