Convergence International The non-Wintel user group, supporting Acorn, Amiga, Apple, ARM, Be, NCs, PowerPC, Psion, Unix and other alternative operating systems. Services include a non-Wintel news summary.
http://www.convergence.org/ More Info
How Stuff Works: Operating Systems Unbiased enlightening tutorial with impartial description of how OSs work, and many related links.
http://www.howstuffworks.com/operating-system.htm More Info
Internet Operating System Counter Statistics on Internet OS use, WWW, FTP, and News servers. Over 940,000 hosts checked in this 1999 survey.
http://www.leb.net/hzo/ioscount/ More Info