Normally, I'm against putting flashy stuff onto your bike, car, etc. in an attempt to grab attention. But this little item is not only flashy, it'll increase your safety on the bike:
Check out the Down Low Glow! It uses a rechargeable battery, throws a halo of light around your bike for 10 feet, and comes in six colors!
I don't think it'd be possible to miss someone with this on their bike at night! So much for the "I just didn't see him" excuse from motorists!
I'm currently checking with the Columbus Police to see if there are any sorts of restrictions on such lights (colors, etc.).
People, not speed.