For an evening commuter or late-night rider, being seen from the rear is perhaps more important than being visible from the front. Use the CherryBomb .5 Watt Tail Light from NiteRider to help alert motorist that you're out on the road too.
NiteRider incorporates a multi-directional collimator to focus the light from the LED and to disperse it to the sides of the rider as well as the rear. They have also made use of a customized reflector that will keep you visible even when the taillight is off.
The NiteRider CherryBomb .5 Watt Tail Light has pocket clip and bike mounts so that you can have several options for attaching it to your back end. It offers a flash mode and has a run time of up to 100 hours, and it uses three standard AAA batteries. At just 76 grams, you can't possibly have an excuse for not being visible.