Chad sent a link about gas bag vehicles to me today. I'm not sure why I had never heard about this topic before, but I found the article very intriguing. The site has many other interesting articles in addition to this one. Be careful though, as the site will suck you in if you're interested in alternative power sources and such. I encountered an article on the site that discussed oil well jerker line systems that I recognized from the Robinson, IL engine show that I attended two years ago. There was one article on hand powered tools. Cool stuff here for sure.