Luca is building a Nixie clock, and in this post he covers the high voltage power supply section.
Nixie tubes are digit displays that use ~170V between the digit wire and a wire mash, to agitate the gas inside the tube. This surrounds the digit wire with a orange glow and it becomes visible through the tube.
Luca is using the MAX1771 based DC/DC boost converter to supply the high voltage required. This DC/DC steps up the 9-12V input to 180V output, as a bonus it has an additional 5V output for the rest of the circuit board.