Linux Mobile System (1,487)
LMS is a GNU/Linux mini-distribution within a USB Flash Memory Drive. This system will be able to boot from any x86 based PC, so we can to run a lot of utilities: network diagnostic, disk diagnostic, etc.
Lycos' UNIX Guide (1,679)
A brief overview of some of the more often used UNIX commands, in an easy-to-understand format.
A very thorough BSD news site. Contains a lot that may not apply to Mac OS X, but also some good general UNIX articles and links to tutorials.
mySQL Tutorial (2,227)
A great walkthrough for mySQL beginner's on what to do with their newly install mySQL database program. Covers security, administration, database and table creation, etc.
Ohio State's online UNIX course (3,519)
A very thorough introduction to UNIX, presented in a series of HTML pages. Also available as a PDF or Postscript file.
Very nicely done, especially for those new to UNIX.
A completely non-Apple-controlled site for future open source enhancements to the core Darwin OS. While Darwin has always been open source, committing changes to the source has been difficult due to Apple using Darwin to build OS X. OpenDarwin.org is a completely independent site that will allow easier commitment of source changes.
OS X for Oceanographers and Atmospheric Scientists (1,533)
OS X customizations for scientists, especially those working in atmospheric and oceanic sciences. Includes information on OS X ports of popular unix packages for geophysical analysis and visualization.