Some things I learned while running Debian on these machines.
Keyboard tricks
command == apple key
option == alt key
cmd-opt-p-r Zap PRAM. Hold down until second chime.
cmd-opt-o-f Boot into open firmware
cmd-opt-n-v Clear NV RAM. Similar to reset-all in Open Firmware.
cmd-period When OF system picker is active, open the CD tray
much more mac specific keyboard tricks - thank you!
Setting the right video mode
Different kernel command line parameters for the setting the right video modes for different models.
Open Firmware
An introduction to Open Firmware for people who just want to use it :)