magiclantern.fm/

Magic Lantern is a firmware add-on, originally written for the Canon EOS 5D Mark II by Trammell Hudson in 2009, and ported to the 550D/T2i/Kiss X4 (1.0.8) in July 2010 by the same author. The current principal developer is known as A1ex and there are now versions for most Canon DSLR's.

Current features include:
- Audio controls, on-screen audio meter, audio monitoring via A/V cable
- HDR video, bitrate control, FPS control, auto-restart
- Precise ISO, White Balance, and Shutter Speed controls
- Zebras, false colour, RAW histogram, waveform, spot meter, vectorscope
- Focus peaking, 'magic zoom', trap focus, rack focus, follow focus, motion detection
- Automatic Exposure Bracketing, focus stacking
- Intervalometer, bulb timer (up to 8 hours), bulb ramping
- Custom cropmarks/on-screen graphics
- On-screen focus and DOF info, CMOS temperature, clock
- Customizable menus and scripting
- Customizable "P" Program mode
- 14-bit RAW video on some DSLRs
- Dual-ISO for increased dynamic range up to about 3 EV, with trade-off of somewhat less resolution and more complicated post processing involving cr2dng
- Auto-Dot-Tune on some DSLR's for automatic micro-focus-adjustment to calibrate lens and body (5D2, 6D, 50D, 5D3 and 7D)

Planned future features include clean HDMI output, anamorphic preview and custom curves.

http://en.wikipedia.org/wiki/Magic_Lantern_(firmware)