Below is a link to a great website that has specs, links to reviews, and links to prices on just about every digital camera.

Personally, I would not buy a camera with less than 1024x768 resolution at this time. Even when you scale the pictures way down for use on the web the ones that start out at a high res are much sharper and more detailed than those that start at 640x480 (ie. even if you want to end up with a 640x480 image you will get a much better one by taking a 1024x768 original, adjusting it in PhotoShop or similar program, and then scaling it down to 640x480).

You can see some comparisons where I took the same exact shot with both a 640x480 and a 1536x1024 camera and then scaled down at http://www.pete-and-lisa.com/pete-o-vision/hikes/phleger_12_12_98/index.htm