So these guys connect some LEDs to a battery and a magnet and throw it up so it sticks on the side of a building.

Internet Week article

Here's their website:

graffitiresearchlab.com

You can bypass the too-long video by clicking on the link below it. It will bring you to an instruction page along with some discussion by people who don't all agree it's a good thing. Obviously some minimum-wage janitor will have to go out in the morning and remove all the high-tech litter on the side of his boss's building. I hope he doesn't fall off the ladder just because some kids decided to deface the building.

I know in my heart that man is good.
That what is right will always eventually triumph.
And there's purpose and worth to each and every life.
- Ronald Reagan