Milsim Paintball Fan
"I find your lack of faith disturbing."
Forget typical mask mounted fans, if you really want to get an awesome defogging system, somebody should look into tricking out the new AVON EZAIR system.
Now obviously this isn't a serious call to implement this exact system, but it nevertheless would be quite fun to see a mask manufacturer created a modular breathing (and maybe communications) unit built into the paintball mask. I know there are some manufacturers that used to build in compartments for communications systems in their masks (and Angel was claiming to do so with their Eyes Goggles), but it seems to have fallen out of common practice, and there are even fewer that have elegant fan/cooling solutions.