Here be some quickly thrown together retro-computing links.
Below are a list of museums with wide collections or at least collections not necessarily specific to a certain hardware platform. The archives listed also contains information about lots of platforms, operating systems and other software.
Charles Babbage Institute, University of Minnesota
Eric Smith's Retrocomputing Links
Karl Kleine's collection of Historic Documents in Computer Science
Bitsavers - Al Kossow's huge document and software archive
Eric S. Raymond's Retrocomputing Museum
Blinkenlights Archaeological Institute
Classic computers at Blinkenlights
Henry Baker's Archive of Research Papers
Marc Crispin's Panda distribution of TOPS-20
Tim Shoppa's Archive of PDP-10 and PDP-11 Software
Stu Grossman's KX-10 PDP-10 Emulator
Ken Harrenstein's PDP-10 Emulator KLH-10
Bob Supnik's Emulator System SIMH (many platforms)
Björn Victor's notes on getting ITS running on KLH10
Tom Hunter's CDC 6600 Emulator
The Hercules IBM Mainframe Emulator
CBT Tape Archive. Includes MVS version 3.8, VM/CMS release 6, DOS/VS release 34, TSS/370 version 3).
Jay Maynard's collection of PD IBM software. Includes Volker Bandke's Turnkey MVS, if you are so inclined, and Andy Norrie's ready-to-run VM/370 system.
Michael Koehne's instructions on how to install MVS, VM et cetera.
MIT CADR Lisp Machine Emulator
Björn's notes on running a CADR emulator (hosted by ITS!)
Microbee Software Preservation Project (MSPP). Also hosts Stewart Kay's Microbee emulator.
Warren Tommey's The Unix Heritage Society
Tom Van Vleck's Multics Archive
Incompatible Timesharing System (ITS)
Dan Murphy's TENEX and TOPS-20 Papers
HOPL: an interactive Roster of Programming Languages at Murdoch University, Australia.
The Language List - Version 2.4, January 23, 1995. This is a local copy I've had for many years. I don't know if there's still a version that is continously updated. It's useful, nonetheless.
Much information about Edsger Dijkstra at University of Texas.
Dennis M. Ritchie's own homepage at Bell Labs. He keeps a lot of texts and images of historical importance.
Information about computer pioneer Konrad Zuse at Technische Universität Berlin, Germany.
Postel Center's Computer History List.
Postel Center's Internet History List. Archive.
alt.folklore.computers newsgroup