These are not the best photos but I snapped them with my phone in the rain last night to see how my need spoke, fork and seat stay reflectors work.

I think they up the visibility level somewhat and my fred status. They are just cheap four inch plastic pieces from deal extreme. They snap on securely for now. They should be easy to remove also.

On the spoke and seat stay is just reflective tape I bought at MEC.

I also just installed a new set of Marathons so they have only seen one ride and have not gotten gunked up yet.