Retinal Eclipse
Agnes Heyer :: Currently unavailable for freelance work

Pixeljoint
I use Twitter to post pixel art doodles and game art. My larger pixel art pieces can be found on Pixeljoint.
Creative Commons pixel art
Mainly tile sets, but also other kinds of pixel art for games, licensed under a CC BY-NC-SA license.
Dinothawr
Dinothawr is a cross-platform freeware puzzle game with 50 levels.
Contact
Email me, or message me on Twitter

Other stuff
A guide to making pixel art tile sets using templates