I think I talked about this on my site but I finally was able to get a hold of the pictures.
At work we saved our cans for about 2 months in order to play a prank on our resident eco-girl. She recycles everything so we thought a gigantic tower of cans on her desk would be a good prank.
We saved up approximately 700 cans and stacked them on the desk. It surprising how unstable a can tower can be. We had to reuse the plastic loopy things to help hold it together.
http://excalibur.rayd.org/mainpage/tower1.jpg
http://excalibur.rayd.org/mainpage/tower2.jpg
http://excalibur.rayd.org/mainpage/tower4.jpg