I spotted maker Tubetime wearing this beautiful DIY nixie tube necklace at Maker Faire. He made an interesting mechanism that enabled him to step up the voltage from a 3v coin cell battery to the 150v that the nixie needs to run(!). It's one of the most beautiful nixie projects I've seen. Great work- and check out the rest of his Flickr stream-  he's got some amazing projects, and he's a great photographer.