Lights for your bike.
The main advantage to me is they run on standard batteries (make use of your Eneloops, not disposable silver cells or otherwise) so I thought I'd give them some attention here.
These seem pretty good to try out and that wrap-around lighty pinstripe string could have some use away from the bike too.
YouTube video (from woot)
http://www.youtube.com/watch?v=lScKfQCzsc8
manufacturer info
http://www.meonbikefx.com
Let us know of any better alternatives in the comments if you use them.
Seems like a good gift for kids and LED fans.
Further reading seems to suggest that each light only shows up on one side of the wheel; keep that in mind.