I installed a pair of Cateye Orbit lights after having a few close calls from drivers approaching from side streets and driveways. These are spoke mounted lights with an amber color. The motion of the lights as they orbit around the wheel is very eye catching and immediately recognizable as a bicycle.
Since installing, I have noticed that motorist see me much sooner. I also use two Night Rider MiniNewt mounted on the handlebars, and a Dinotte taillight mounted on the seatpost.
Cateye Orbit
http://www.cateye.com/en/product_detail/576
Pros:- Affordable. $20 for a pair
- Amber colored has universal meaning as "side light"
- Orbiting light motion is immediately recognizable as a bicycle
Cons:- Uses CR2032 batteries which are more expensive to replace than a AA or AAA
- Weight of light makes wheel slightly out of balance
- The lights become dirty from road spray and require regular cleaning
- Lights could be brighter, but then the battery would be heavier