Atari 800 Web Server: A simple web server (in Atari BASIC) that sends a hardcoded page via a terminal server.
APE Homepage: Use your PC as a LAN server for your 8-bits!
XL Search: Search for Atari 8-bit files.
atarimagazines.com: Formerly the Digital ANTIC project. Online copies of ANTIC, Compute!, and other magazines of the era.