Is bitcoin Jetsons-level crazy? Maybe, but it's also starting to look like more than a geek-fueled fad. While bitcoins are not the only form of cryptocurrency (ripple and litecoin are others), they appear poised to become the world's first to go mainstream. Microsoft now accepts bitcoin for Windows and Xbox purchases. Overstock.com and Amazon.com take it. You can spend bitcoin at Home Depot, Kmart, CVS and Sears. Newport Beach Lamborghini in California recently sold a Tesla Model S electric sedan for the equivalent of about $100,000 in bitcoin. BitPremier, the leading Bitcoin luxury marketplace, sold a villa in Bali, Indonesia, worth nearly $600,000 in what is believed to be the largest bitcoin purchase to date. Heck, if you want a private, $250,000 ride into space, you can pay Virgin Galactic with bitcoin too.