Duke3D Source Portal
Directory of all projects based on the Duke 3D source release.
FileShack.com: Duke Nukem 3D Source Code
Includes a download of the source code for the game.
JT's Duke 3D Build Center
Includes news, downloads, Build resources, and related links.
The Duke Nukem 3d Level Editors' Homepage
Contains build help, links, maps, and rts files.