If the camera is for your son or daughter you may want to buy a camera which is made for children, such as the Nintendo Game Boy Camera and the Mattel one that's Barbie-branded. Computer screens don't have very high resolutions -extra pixels go to waste if you're only using the camera for emailing and the web. A 2 megapixel camera is more than plenty for those uses. If you plan to take action pictures, be sure to look into what the lag time is between shots. The camera should also include some form of red-eye reduction.
Some cameras have the capacity to take very short video clips and some can even capture sound.
The Active Buyer's Guide helps you figure out how you will most likely use your camera and tries to find an ideal one for you. Cameras today generally go as high as 3.34 megapixels which is an image resolution of 2048 x 1536. If you're not a professional or planning on printing poster-size images, the odds are you'll do fine with 2 or less megapixel, however, the resolution should be noninterpolated. In a similar vein you're better off if the camera has an optical zoom. A digital zoom isn't as clear.