I haven't made any of these.
WEBSITES
Reiners (Sprites & Tiles. 2D ISO) - http://reinerstileset.4players.de/
Gitorious (Tiles. 2D and 2D ISO) - http://gitorious.org/tmwdata/mainline/trees/master/graphics/tiles
The Mana World (Tiles & Sprites. 2D) - http://forums.themanaworld.org/viewforum.php?f=8
Zanyzora's RMXP Resources (Tiles & Sprites. 2D) - http://www.teamanti.com/rmxp/
NES / SNES Sprites (Sprites. 2D) - http://www.nes-snes-sprites.com/
The Shyguy Kingdom (Sprites. 2D) - http://tsgk.captainn.net/
More coming soon (maybe). It surprised me how many sites were down.