"If you're using a consumer grade point-and-shoot Canon digital camera, you've got hardware in hand that can support advanced features way beyond what shipped in the box. With the help of a free, open source project called CHDK, you can get features like RAW shooting mode, live RGB histograms, motion-detection, time-lapse, and even games on your existing camera. Let's transform your point-and-shoot into a super camera just by adding a little special sauce to its firmware."--Lifehacker
CHDK--Canon Hacker's Development Kit.
What can CHDK do --
- Enhanced Image Capture: CHDK supports RAW format for pictures (in addition to JPEG), longer recording time and length for videos (up to 1 hour or 2GBs), and several new compression options.
- Additional Information On-Screen: With CHDK, you can customize your on-screen display to your heart's content, including worthwhile information like remaining battery life, histogram, depth of field, and more.
- Additional Photographic Settings: CHDK takes many of the features already available on your camera and gives you way more options, including longer exposure times (more than 65 seconds), faster shutter speeds (1/25,000 sec or faster), automatic bracketing of your photos, and more.
- Support for Small Programs/Scripts: CHDK can run small scripts that will allow your camera to perform a set of actions based on the conditions of the script. Tons of scripts are available, and they provide functionality like motion-sensing photography (which reportedly works for lightning strikes) and unlimited interval time-lapse photography.
Sometimes porting for your camera might be W.I.P. so use google to find appropriate porting forum thread.