Sorry, I had to do this. Tour de Fat is coming to Chicago this year on July 21st (and Milwaukee, Wisconsin on July 14th). Sponsored by the New Belgium Brewing Company, it's a combination of (as per a 2010 article in SFGate), "bicycles, beer, entertainment and do-gooding." People dress up in costumes, there are lots of unusual and inventive bicycles in a big parade, contests, a stage with entertainment and the culmination of the event, a car-for-bike swap in which one winner makes a commitment to go car-free for a year, turns in their car keys and is given a bicycle. The car is then auctioned with the money going to charity (actually, all the proceeds from the event goes to local bike advocacy programs).
The event uses only sustainable energy and compostable materials.
Here are some of the more interesting bikes from a 2010 event (this is the crazy bike rodeo).