So I found this guy on eBay selling an iSight that he took out of his Macbook. So here is my question: I have an 800 MHz G4 flat panel iMac. How big of a project, if any, would it be if I purchased this iSight and used it for my desktop?
There is no way to connect that to your iMac.
While it may lie in the realm of possibility, it would be a rather labor-intense and expensive project that could end up damaging your system. Basically, your chances of doing anything with it are extremely slim.
If you want an iSight, I suggest looking for the discontinued external one.