The Extracycle

So I found this bike company called Xtracycle and I'm all about their Free Radical system. Theres a video of how it works here. It elongates your bike so you can carry more stuff. I wonder what I could haul around on this? There's a guy that goes on rides in Austin on one of these and has this huge sound system on the back of it with lights. Surly also makes a frame.