Here is a little bit about choosing a webcam from
my company
How to Choose a WebCam
Number of Pixels
The number of pixels is often NOT the most important thing when choosing a webcam. Before you spend much on a webcam, consider what you will be using it for. First let me point out that many models of "digital camera" can be used as a webcam. For instance, I have a Fuji digital camera that I have used many times as a webcam. If your digital camera connects to your computer with a USB cable, or a "1394" cable to get the pictures out of it, you can probably use it as a 'webcam'. In my Fuji, there is a menu for setup. One of the choices is whether to transfer pictures (just like copying files from one folder to another on your computer) or to use it as a "pc camera". In my case, I use it as 640x480. But the big advantage it has over a 'webcam' is that the "digital camera" can operate is fairly low light and very bright light, like out in direct sunshine. And it has great focus range and zoom. When I am copying 8mm movies from film to the computer I always use my "digital camera". So if you already have access to a 'digital camera' you might want to try using it for a while until you decide what you really want in a 'webcamera'.
Light Sensitivity
Most webcameras can not be used outside in the day because the sun is too bright for them. Also, they can not be used in the evening, or even inside unless you have lots of lights on. They do not have an iris so there is not much you can do about this except turn on more lights. Or when outside, hope for lots of clouds and a big shade tree.
Power for the camera
Almost all webcams get their power from your computer over the USB cable. (Using my Fuji digital camera it goes through a set of 4 AA alkaline battery in about 2 hours.)
Focus
For general use on the internet, live conversations or video email, you probably will never need to adjust the focus. Most webcameras have permenant fixed focus. If you want to show close ups (like I show circuitboards and test fixtures) then I need manual focus.
Speed
One difference in the very very cheap webcameras and 'more expensive' ones (like $35 or more) is that the cheapest ones can only do 15 pictures per second. That is usually enough for "video instant messaging" or casual conversation between hearing people. But with sign language, you probably will see a big difference in getting a webcam that can do 30 frames per second (if your video email or your 'video instant messaging' service can go that fast). If you are stuck with dial-up internet access right now, then the faster camera will probably not make any difference.
Stand / support
Where and how do you want to use your camera ? For business trips I use a Logitech "notebook" camera. It clips onto the LCD display of my laptop. However, at home in my laboratory, I use a regulary "ball shaped" webcam that can sit on top of the CRT monitor. But I usually have that camera clipped into a flexible microphone stand on my desk. (It is called a 'gooseneck stand' and it is a little over a foot high.) I can aim the camera anywhere. It is great to aim the camera straight down onto my workbench to show what I am doing.
Ruggedness
If you webcamera is going to be on top of your CRT monitor or in a stand on your desk all the time than this is not a factor. But if you want to toss it in a bag to bring with you to a friends house or on business trips you want to keep in mind that lenses can get scratched very easily. For occasional trips, just wrap it in a soft rag. The logitech "notebook" camera comes with a small padded bag. The ball-shaped cameras have the lens recessed 1/2 an inch or so so that the lens is sort of protected.
Indicator Light
Almost every webcam I have seen has a light on it to show when it is active. This is very helpful to let you know that the computer software is working (at least partially). Also, it is nice that the light reminds you that you have left your computer running and who-knows-who might be watching you change clothes.
