1) Shift (On Boot) - Safe boot, loads no kernel extensions
2) Shift (On Login) - Safe login, doesn't launch startup apps
3) [command + v] - Verbose boot, shows what files are loading, useful if all you see is the "pinwheel" forever.
4) [t] - Target disk mode, turns Mac into an external hard drive, firewire only, useful for retrieving files.
5) [c] - Boot from CD or DVD
6) [d] - (While Install DVD 1 is in drive) Starts Apple Hardware Test
7) [mouse button held down] or [eject] or [f12]- Ejects all removable media
8) [command + s] - Single user mode
9) [command + option + p + r] - Resets parameter RAM. Mostly voodoo, but never hurts.
10) [command + o + f] - (PowerPC Macs only) boots into Open Firmware
11) [option] - Display boot menu
12) [Command + r] - Boots to Recovery Partition in Lion ONLY
13) [power button] - holding for 5 to 10 seconds resets the SMC(System Management Controller)
Enjoy :)
