Macintosh OS X

Apple Developer Join the Developer's Connection.
Mac In-Touch Daily dose of questions, problems, and news.
FAQ for OS X Frequently asked questions and links to useful sites.
Resexcellence Guide to the underpinnings of OS X.
Mac Update ditto
Mac Observer News and commentary.
Macworld Look for the discussion boards.
Geek Culture satire
Westwind Lots of info. Look for the guide to the commandline instructions in Terminal.
Unix for Beginners A free web-based tutorial.