When I read this thread, I knew I had to go out and get a pair for myself. Spent a little extra for presta-shraeder adapters (wish there were plastic rather than metal though).

Got the UV Yellow. Very bright. Very cheap... got a pair for $8 at Wal*Mart (the shame of it).

It seems that the activation of the lights has less to do with the spinning and more to do with the natural bumps that occur while moving. Put the bike on a stand and turned the pedals; they wouldn't turn as there wasn't enough acceleration to activate them, but just a little bump while rolling on pavemet was.

I was interested in hokey spokes, but they cost too much and they gave no discount for buying 3. Given they said you needed at least 3 to have nice patterns, they should sell as 'starter kit' of three.