I stumbled onto the Universal Access preferences pane yesterday and found a few nice bonuses:
First off, under Hearing, you can set it to flash the screen whenever there is an alert. Nice when the audio is muted or iTunes is crankin'.
Secondly, for late night coding sessions when eyes are fried and monitor brightness won't go any lower, Switch to White on Black comes to the rescue (control-option-command-*). The photo is from a heavy duty full-screen zoom while in White on Black mode.