Trailing-edge.com
- PDP-11 freeware CDs.
- http://www.trailing-edge.com/www/freeware.html

pdp11.co.uk
- Information, pictures and profiles on the PDP-11 family of computers and peripherals.
- http://www.pdp11.co.uk/

YAPP
- "Yet another PDP-11 Page", from John Holden.
- http://www.psych.usyd.edu.au/pdp-11/

RSTS-11 Library Entries
- Compiled by Tim Shoppa.
- http://pdp-11.trailing-edge.com/rsts11/

The PDP-11 Unix Preservation Society
- Devoted to the preservation of all information related to the versions of Unix that ran on Digital PDPs.
- http://minnie.tuhs.org/PUPS/index.html

Pdp11.org
- Dedicated to preserving the history and legacy of the PDP-11 series of 16-bit minicomputers.
- http://www.pdp11.org/

Metalab.unc.edu
- PDP-11 freeware archives.
- http://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/

The PDP-11 FAQ
- Information for those who are enthusiasts, curious, or downright confused as to what the -11 was and is, and how it related and still relates to its world.
- http://www.village.org/pdp-11/faq.html

Mentec
- PDP-11 operating systems plus layered products and services.
- http://www.mentec.com/