Motorcyclist here. I have a Drift Stealth 2 [1] and have it mounted on the side of my helmet. I like it because the form factor is just so good. All the GoPro mounts I've seen seem to stick out from the side of your head awkwardly and look like some kind of antenna. You can get it here [2] with a 10% discount if you use the code VLOGHIM.
Ditto with a Drift HD Ghost, although the Contour cameras seem like they have an even better form factor. I like the fact that the Drift is waterproof out of the box too, no case needed.
Techmoan has extremely detailed action camera reviews, with raw sample footage, and often takes them out for a ride (weather permitting, he's in the UK after all!).
http://www.techmoan.com/blog/category/action-cameras
Please be careful with helmet mounts. There have been some serious injuries attributed (maybe incorrectly!) to rigid mounts transferring energy in ways helmets aren't designed for.
1: http://store.driftinnovation.com/cameras/drift-stealth-2 2: http://actioncameras.co.uk/