I got this:
http://www.amazon.com/Sona-Enterpris...4049868&sr=8-4 off amazon. The LEDs help cars seem me even if their headlights aren't shining directly on me.
I've stopped using it, though, since I bought reflective tape and basically outlined my bike, with mulitiple strips in the front and back, and have two front and two rear lights (planet bike super blinky lights in the back)