Every time I have to take a screenshot on my Mac, I'm all "What was it again? Hold down the Command key, stand on my head, press F4, cross my toes and pray...?"
Turns out in OS X it's Command-Shift-3 that will buy you a PDF file of your entire screen. Too bad 10 times out of 10 I don't want a PDF, and I don't want the whole screen. Thanks to O'Reilly's Screenshot Hacks for Mac OS X, I re-remembered that OS X ships with a Utility program called Grab, that will capture sections of a screen, or do timed screen shots that will capture pointers and selected menu items as well.
Useful.
Screenshot Hacks for Mac OS X [macdevcenter.com]