Useful things arrive here when I find them.
This is a pearl script that will compare two latex document and highlight any significant differences, red and struck through for deleted and blue for added, in much the same way as track changes would in Word (spit). Very useful for working on manuscripts with multiple authors.
A really neat solution to the perennial problem of locking your screen, windows style (yes they got some things right), on a Mac. Unfortunately, as far as I know this will only work on 10.6 up.
A great site to offer an introduction to unix on your mac.
OSXFAQIf you install Mac Office 2008 to try it, because it runs natively and so should be faster/better. When you find out that it is awful and has ruined your life, AppZapper will easily remove all trace of it for you.