Wonderful world of Aerogel

If you have never heard of aerogel then know this. It is the worlds lightest solid in at only 3 times the weight of air. It is listed in the guinness book of world records for that fact as well as being the best insulator man is aware of and 13 other records. This stuff is apprently difficult to manufacture and is for that reason pretty expensive. I saw a piece measuring 6"x6"x0.5" going for over $4,000 on ebay recently.