Galleries
Hardware Gallery - pictures of the system, accessories, and prototypes
Game Boxes - a guide to the various styles used for the 7800

Reference
Atari 2600/7800 Technical Document
Atari 7800 BIOS Disassembly (29KB asm)
Atari 7800 Compatibility Modification (external link)
Atari 7800 Encryption Algorithm Technical Documentation
Atari 7800 Schematics - NTSC
Atari 7800 Schematics - PAL

Game Strategy
Karateka Strategy
Super Skateboardin' Map