I have a GoPro Wide. Used it twice so far. Mounted to Roll Hoop. First event I didn't have the sound set correctly so the camera picked up pushrod noise and the run audio made my engine sound almost F1.
The firmware upgrade for the "wide" is available to allow more storage per card. However, battery life is about 2 hours with the best rechargeables and 3 with the best non rechargable lithiums. If you get a GoPro you will need to format the memory card regularly to actually get the recording time. However my Canon point and shoot says the same thing for movies so I assume it is similar to the need to defrag hard drives.
There are lots of more expensive options out there. ApexSpeed has numerous threads. Reviews for all the options are mixed. Lots of love/hate.
For example:
http://www.apexspeed.com/forums/showthr ... hlight=pov
Also search GoPro.
Here are a couple of mine plus a couple of Bernard Cooley's
http://www.youtube.com/watch?v=tChSojdbz7s
Second event got the sound correct but had one mount bolt a little loose so the camera tilted a bit.
http://www.youtube.com/watch?v=d8sPGqw_E0c
Note that the course are slightly different even though they look very similar. The car had VERY stiff springs.
Also, see a couple of Bernard Cooley's runs. One at VMP and one at the Nationals. He uses a Flip Video camera.
http://www.youtube.com/watch?v=punFgrK-qkM
http://www.youtube.com/watch?v=txEbCbPOylE