I am also very interested! This will be very helpful for my current project.If anyone is still interested, I currently have an iMac G3 working as a monitor for a separate PC, with the original iMac motherboard removed. Apart from the motherboard being removed, the rest of the original iMac hardware is intact. It was a bit complicated (there's an Arduino sitting in the iMac making everything talk nicely), but works well. If there's any interest in it I can pop up some details.
Thanks in advance!