Web page at Courtesan Consulting
Pseudo, shareware by Brian R. Hill, launches Aqua applications as the superuser or root.
Marc Liyanage's page of Unix software includes MySQL, packaged for Mac OS X.
Admin.com is the companion site to
UNIX System Administration Handbook,
by Evi Nemeth, Garth Snyder, Scott Seebass, and Trent R. Hein (Prentice Hall, 2000).
Unix Guru Universe is the official home page for Unix system administrators.
This link will bring you to "Mac OS X 10.0: About the root User and How to Enable It" from Apple's Tech Info Library.
SecureMac.com includes security lessons and information for Mac OS X.