Links

Site Description
Battle for Wesnoth Wesnoth.org is the home of one of the shining stars of the free/open source gaming community, Battle for Wesnoth. In addition to the game itself, this site also hosts an active general open source game development forum.
BlenderNation A news site and forum dedicated to the open source 3D content creation suite, Blender.
DeviantArt Probably the biggest art community on the web.
Les Forges Les Forges is a pixel art website in French. Even if you don't speak the language, I highly recommend firing up Google Translate and reading some of their art tutorials, which are absolutely stellar.
OverClocked Remix A video game music remixing site. While not directly related to open source, it has an excellent forum for composers.
Pixel Joint A pixel art community.
Pixelation From their faq: "Pixelation is a message board about pixel art, first and foremost. Its role is to provide a setting in which people may sharpen their skills by posting work and receiving critique from others, and to offer critique when others...
The-Blueprints.com Free blueprints for various cars, planes, military vehicles, etc.
Toolkit Zone The official home of RPG Toolkit, an Open Source RPG maker.