How To Install Chdk On A Canon Powershot Camera - Youtube Video

Installing CHDK on a Canon PowerShot Camera - Canon Hack Development Kit

CHDK Main Features

Professional control - RAW files, bracketing, full manual control over exposure, zebra mode, live histogram, grids, etc.
Motion detection - Trigger exposure in response to motion, fast enough to catch lightning.
USB remote - Simple DIY remote allows you to control your camera remotely.
Scripting - Control CHDK and camera features using ubasic and Lua scripts. Enables time lapse, motion detection, advanced bracketing. Visit the CHDK Wiki for more.