The under $600 market is tough. The Canon ZR series is in that range. They're ok, but suffer in low light.
Make sure you get a camera with an external mic jack because the built in mics stink and you'll want to get a decent shotgun mic (Azden makes some ok inexpensive mics). Also, look for manual exposure controls. Auto exposure will work 60% of the time, but will screw you for arty shots.
If you can find a few more bucks the Panasonic GS70 is a 3 chip alternative at around $800.
Scott