1. I Promise It Will Always Be This Way, Jon Sasaki
He got about a dozen of his buddies to dress up in ridiculous mascot costumes at Lamport Stadium to try and whip up the crowd... (a.) with typical stadium music, (b.) for 12 hours, and (c.) with no actual sporting event on the field. Some of the mascots waved pom-poms, slept on the field (much to the dismay of the crowd chanting "Bum-ble-bee! Bum-ble-bee!"), wrestled each other, chilled out with their heads off, or haphazardly danced to the music by themselves off to the side. It was so absurd and random, yet brilliant... my sides hurt from laughing. (Update!!! Video here.)
2. SMASH! Droppin' Stuff, The Custodians of Destruction
Get a SkyJack scissor-lift, load it up with TVs and computers and kids' toys and chairs, and throw 'em down from 25 feet up. Think about your trash, people!
3. Stereoscope, Project Blinkenlights
Take both halves of City Hall, put lamps in all the windows, and have an entire building act like a pixelboard video display, for a very cool effect. (Tough to take a picture of, because of the darkness and the motion of the picture.)
In conclusion... art!!!
(photos courtesy of SA, used without permission)