This camera module can be a pretty neat project addition. It was designed to be used in security systems and does two main things - it outputs NTSC video and can take snapshots of that video (in color) and transmit them over the TTL serial link. You can snap pictures at 640x480, 320x240 or 160x120 and they're pre-compressed JPEG images which makes them nice and small and easy to store on an SD card. Perfect for a data-logging, security, or photography project.
One nice thing about this particular camera is all the 'extras' that come with it. For example it has manually adjustable focus, auto-white-balance, auto-brightness and auto-contrast taken care of for you as well as motion detection built in! That means you can have it alert your project when something moved in the frame.
We also carry an enclosed weather-proof version
Using the module is pretty easy and only requires two digital pins (or a TTL serial port) - by default it transmits at 38400 baud. Of course they wouldn't just leave you with a datasheet and a 'good luck', they even spent a lot of time researching the module and DSP to make a really nice Arduino library with example code that shows how to change the image size and compression quality, detect motion, control the video output stream, etc. That and more is available in their very detailed tutorial that will help get the most use out of your camera.
Example photo 1 (outside street) & example photo 2 (inside person)