Eric writes (and from the MAKE Flickr pool):

Someone at the Maker Faire challenged me to turn a working nixie tube into jewelry. Here’s a “glowing cross” steampunk-style pendant. It uses a CR2032 coin cell battery to run the high voltage power supply. It uses less power than an LED throwie.

I don’t know what’s better, this project or the fact that it was conceived at Maker Faire.