We've had some problems where I live with car drivers who drive too closely to cyclists, so I decided to video my daily bike ride to work each day. Long story short, it made more sense to use a head-mounted camera than to attach one to the bike. (Vibration, view angle, etc)
Fortunately I already owned a micro-camera, the only challenge was to find a way to mount it - and you can see the solution in the photo above.
Step 1: Materials
* Micro video camera ($13)
* Head-mounted lamp ($3)
These Micro DV cameras range in price from maybe $90 to $13 shipped. It may depend on whether they're being sold in a spy store or as a toy for children :-)
The head-mounted lamps are all over the place now. Mine was a cheap one from China which was already broken, so I didn't mind dumping the flashlight to free up the headband).