NASA has designed a product called Aerogel, also known as "frozen smoke". It is 99.8% air. It is used in space shuttles and can endure temperatures higher than 2,500 degrees farhenheit and is the most powerful insulator on Earth. Think of the money it could save you if you had it in your home! I'm not sure it is on the mass market, but it is really cool and I think NASA should put it out there.