I found this how-to on Gizmodo the other day. I've heard of such projects before, but this one includes demo pictures, which are surprisingly good quality considering the price of the camera. I'll probably try this out sooner or later:
http://www.elephantstaircase.com/wiki/index.php?title=TenDollarDigitalCamera
It doesn't mention if it's OS X-compatible; if anyone tries this, be sure to report back.