CCD tutorial

I found this on dpreview. Its an excellent tutorial on CCD sizes. The sensor is 1/3 of the formula of picking the camera (Megapixel, sensor, lens). While the lens is the hardest to research (unless you are buying a high end SLR) the sensor size can be found on several good websites - including dpreview.

http://www.dpreview.com/learn/?/Glossary/Camera_System/Sensor_Sizes_01.htm