Kenneth Finnegan sent me a link to a project that he has been working on - it is an AVR based IN-16 nixie tube thermometer. It appears to be a pretty straightforward design and what I really appreciate about this is that he does a great job documenting his build and sharing code samples with readers. I've included the part list below so you can get an idea of what is involved but be sure to check out his website for more details, schematics, and photos!
Video
Parts list for control circuitry:
1x ATTiny2313 AVR
1x DS1631
3x IN-16 Nixie tubes
3x K155 or 74141 Nixie decoder
3x 22kΩ resistor
3x 4.7kΩ resistor
1x MPSA42 300V NPN signal transistor
Parts list for power supply:
1x MC34063 boost converter (I managed to smoke the first one with 180V pretty quickly, so having it in a socket and having spares is a good idea)
1x 7805 5V linear regulator
1x IRF820 MOSFET
1x 500μH power inductor
1x 1N4937 600V fast-recovery diode
2x 100μF 100V capacitors (or a single cap rated for >200V)
1x 820k resistor
1x 5.6k resistor
1x 150Ω resistor
2x 47μF capacitor (25V)
>2x 0.1μF capacitors (25V) - Apply liberally throughout the circuit