We had a broken ibook G3 on our hands. It had a strange "snow" on the screen, vertical lines in odd patterns across the screen. To retrieve the data we had to set the laptop up as a firewire target. First we rest the pram by pressing - option-apple-p-r, then startup the machine holding down t. Plug in the firewire cable to another mac, and retrieve the data to the new machine.
Things to look out for: