PPTactical: Open Source RTS/Tactical engine.
HGE Graphics Engine: 2D hardware-accelerated graphics engine.
Videobrewery: Hosting for homebrew video game projects.
gameboy advance development: General information about the Game Boy Advance development scene.
Gamasutraexchange: Buy and sell art assets (2D and 3D graphics). This can save the small developer from the expense of keeping an artist on staff.
How do I make games?: An excellent essay on why you shouldn't be trying to produce a competitor to Everquest.
MadMonkey: Forums, info, and links for indie developers.
Free Games Net: Forums, links, and game information.