As so many are intent on posting requests for sprites, I thought it would be a good idea to compile them all in one topic. I have a huge list of them :)
Oh, and I sorted them all into different categories, how kind of me.
MIXED SPRITE COLLECTIONS
http://www.elementgaming.simgames.net/
http://www.emugifs.emuita.it/home.htm
http://www.explore-rpg.com/resources.htm
http://fated-circle.com/
http://www.fireball20xl.com/sprites.html
http://flashstand.com/sprites.php?mode=main
http://www.gaminggroundzero.com/
http://www.gamingw.net/
http://www.gsarchives.net/
http://www.molotov.nu/?page=graphics
http://pages.cthome.net/mnoni/webpage/spritesheets.html
http://www.panelmonkey.org/
http://rpgdragoon.2ya.com/
http://www.rpginfinity.com/
http://www.rpg2knet.com/resources/
http://tsgk.captainn.net/
http://www.sprite-town.tk/
http://www.odinsrealm.com/tatakau/
http://www.vgws.com/
http://www.gifsyndicate.com/
http://www.deekman.cjb.net/
http://www.psyguy.com/
http://www.bladeshotx.com/
NINTENDO SPRITES
http://clik.to/ninsprites
http://www.retrogamezone.co.uk/
http://www.mindspring.com/~hhkyl/vgames/sprites.htm
MARIO SPRITES
http://www.pipehouse.net/sprites.shtml
http://www.classicgaming.com/tmk/yellow.shtml
SONIC SPRITES
http://sfghq.emulationzone.org/sprites/sprites.php
http://www.sonic-gif.com/
ZELDA SPRITES
http://www.zeldaresources.com/
http://www.melorasworld.com/zelda/
http://www.purezc.com/
MEGAMAN SPRITES
http://www.planet-megaman.com/sprites/
POKEMON SPRITES
http://www.pokeschool.com/videogames/rubysapphire/sprites/
http://pokevalley.com/ps/main.php?id=P-Icon
http://www.serebii.net/
--END OF RESOURCES--
There you go. If you need more, consult Google!