How much detail do you want to capture? Anything will be better than a cell phone camera, but usually the cameras with larger lenses will do a better job with taking sharp(er) images.

Just decide how much you want to spend then go to a best buy or fry's and pick one out?

For what you are doing, you might want to steer towards a camera that uses AA batteries so that you can replace them quickly if needed (instead of having to mess with a charger)