Get a cheap digital 8 camcorder that has audio and video inputs and a LANC controller.  A Sony TRV520 works fine, a 525 doesn't - no LANC.

Get a camera from JonesCam.tv.  If you're not going to be in rain, remove the rubber seal behind the lens and add anti-fog to the inside of the lens.

Figure out how to mount the camera, the LANC and store the camcorder.

 Record away.

OK, so that's what I used for all the video currently on my site.  If I was going to start now, I'd probably go this route http://www2.oregonscientific.com/shop/product.asp?cid=20&scid=77&pid=709.  These camera are cheap enough and small enough to have several mounted on to your bike.  The only problem I see is that they only accept 2GB miniSD cards.  I'd really prefer that were 8GB.

My next option would be the JonesCam.tv or Archos PVR route simply for the huge storage size. http://www.jonescam.tv/catalog/product_info.php?cPath=30&products_id=84, or http://www.archos.com/products/video_recording/camcorder.html?country=global&lang=en

Finally I'd look at MotoCam very carefully too.  http://www.themotocam.com/products/MotoCam-dp/

Greg