CHDK is an extended firmware for Canon cameras using the DigicII processor, like my A620
the main feature highlights are
- saving the Photos in RAW mode
- a battery inicator
but there is also
- Live histogram
- Zebra mode (blinking highlights and shadows)
- DOF-calculator
- Scripts execution
- File browser
- Text reader
- Calendar
- Some games
I will post more once I can take a break from learning for the exams with a clear concience.