The CP80-EOS is an active DSLR Cooling System that I have designed specifically for Canon DSLRs.

It was developed to satisfy these three fundamental requirements:

• Cooling Performance
• Control
• Lightweight

Cooling Performance: With the camera working (taking light or dark frames) the CP80-EOS DSLR Cooler can maintain an ambient air temperature as low as 0 C (32 F).
Control: The CP80-EOS has its own Temperature Controller which is remotely wired to the cooler. It allows thermal regulation at +/- 1 C.
Lightweight: The CP80-EOS uses a variety of lightweight materials and components chosen to minimize the imaging load.

Read more about the CP80-EOS project: here