Photography Experiments with CHDK
CHDK means high-end features for low-end Canon compact cameras.
Manufacturers reduce functionality of their compact digital cameras to make them simple point and shoot cameras. Useful 'pro' functionality like auto-bracketing, time-lapse, motion sensing, etc. are not included in the firmware even though they may be physically capable of performing the functions.
Some clever people have developed an improved firmware for the bulk of Canon's consumer digital cameras that provides many (and more) of these missing features. It's called the Canon Hack Development Kit (CHDK).
Select a Camera
The Digital Photography Review site provides all the tools you need to select a camera. I used the feature search pages to find suitable camera models and the model comparison pages to compare different models, finally comparing these and eventually plumping for the Canon A530 based on weight, features, cost and availability.
Some of the extended features I have played around with are: Auto-bracketing; full manual control; extended settings such as shutter times; ability to run scripts; and to use homemade remote shutters.
Follow the links for some of the some cool and interesting projects you can do with relatively cheap Canon digital cameras.