Muris from Elektronika sent me a cool little nixie clock based on IN-16 Russian nixie tubes. Best of all - he published his schematics, documented the inner workings well, and even published the firmware for anyone to build. Right now, you can purchase the PCB's for the kit. He is contemplating offering a kit version of the clock. Visit his site and follow the instructions if you're interested in a future kit version.
1. time display
2. date display
3. temperature display
4. configurable times of showing for all of above (for example, the clock can display time for 20 seconds, and move to next thing to display: date, temperature or both and go back to time. It can even be set to display only the temperature)
5. configurable Nixie tube brightness
6. configurable color of bottom RGB LEDs that blink at 1/2 Hz rate (or even turned off)
7. the "temperature color blender" option that displays blue color at lower temperatures, red at high temperatures and mixes these two colors between these extremes (or even turned off)
8. configurable color of bottom RGB LEDs while displaying date (or even turned off)
9. fading tubes while showing the date for better understanding of what is on display (DD.MM and YYYY)
10. Nixie tube saver option - this option turns off Nixie tubes at defined "sleep" time and turns them back on at defined "wakeup" time (for example, the clock can be configured to shutdown at 23:30 and turn back on at 07:30 in the morning) in order to prolong the life of tubes
11. alarm function with user-configurable melody with snooze function
12. user configurable snooze length with automatic snoozing so that the clock doesn't ring constantly forever if forgotten about
13. Nixie tube cross-fading with configurable fade speed
14. the famous "candle mode" for the romantic "touch"
15. cathode anti-poisoning on every 15 minutes