My son got a set of LED license-plate lighted bolts, like these:
http://www.superbrightleds.com/specs/bolt_specs.htm
We put the things on his cruiser, this weekend. I thought they were gimicky, but when we turned them on and stepped back - WOW. Up close, they just look like a light, but from several feet away, the lenses make a 'star' pattern. The things are seriously visible, out on the road.
I'm of a mind to pick up a set of red ones (natually, he had to use some color that matched his bike - purple). I see no reason why these things won't make some superior additional lighting when installed either as extra tailighting, or brakelighting.
Anyone else tried this?