How much do you want to spend?
Obviously there are the GoPro's and Sony ActionCams, but they are pretty spendy (unless you get an old GoPro).
Forget about buying any the cheaper alternatives locally (ie, the ones that Jaycar, JBHiFi sell).
You can get those for 1/2 the price online (DX, ebay, etc).
Maybe have a look here?http://www.dx.com/c/consumer-electronic ... 0&priceTo=
There are some decent quality cams on there cheap, but you have to do your homework (read the reviews, find un-edited example footage on youtube, etc).
My in car cam works really well, but it's made for a different use. It only has a tiny battery (~10mins worth) and isnt water/dust/shock proof.
Great for in-car, but not much else.
Video quality out of it is amazing though (see my youtube vids from ozgym. 1080p fullscreen. youtube does drop the quality a bit).
It's one of these: http://www.dx.com/p/g50-full-hd-1080p-5 ... ver-323001