DenimGirl:
Most any camcorder with a firewire port will work on your G3 and iMovie, and not just under OS X, but OS 9 too. I have the Canon ZR 30 and it is a great miniDV camcorder. It takes the best video and sound quality I have ever seen in a non-pro camera. I have a graduate degree in media, so I know camcorders. The Canon ZR series camcorders are really prosumer quality for a consumer price.
The ZR 30 has alot of other features (e.g. it can take still photos on a memory card individually, or from and to the miniDV tape). It has a 10x optical zoom and electronic stablization, all very important to getting good footage. You can hook it up to most any TV and use it in VCR mode.
The Canon ZR 30 is a few generations old in the Canon line, so you can pick one up much cheaper than I paid for it a couple of years ago. I seen it go for as low as $385 (I paid $800 US). The ZR 20 is even cheaper with the same feature set, less the still photo memory card. Canon's ZR series is now up to ZR 50, so there are plenty of deals around.
Other brands of miniDV camcorders work just fine for most people. but I recommend a Canon for the best quality and compatibility. I hope this helps you decide.
