Just picked these up myself. Quick and easy front/back warning lights. Not enough to see by but for urban riding (streetlights) at least you can tell others you are there. (Plus clip on and off and kids love to play with them...) Available all over the place and
LLBean. Around $20. If you need a little more uuumph, the
Knog Bullfrog has 5LED's. Stocking-tastic.