Graphics/User interface

Adobe Studio Exchange
Exchange photoshop files, such as actions, brushes, etc.

BitPlane
(portuguese) Photoshop tutorials and downloadable action files.

Efeitos Visuais
(portuguese) Photoshop tutorials

FontFreak
This is a large collection of freeware, and shareware fonts for both PC and MAC.

GRSites.com
This site holds lots of free stuff, like textures, sounds, fonts, etc.

Bitstream Vera Fonts
GNOME
Free true type fonts.

FontSeek
A font search engine that gives results in two groups: commercial and free.

Font Squirrel
A site with lots of fonts that are free for commercial use.

Fonts2u.com
Downloadable free fonts.

Google Fonts
Extensive library of open source and free fonts.