Peter from Axiris.be clued me in to a software nixie clock that he made. It is a Windows / Linux piece of software that emulates a six digit nixie clock. If you don't want to bring your real nixie clock to work, this might just be what you need :)
Update October 2018: It appears that Axiris have transmogified into Elektor, and the software is not available any more. I can't find anything about the clocks any more either. There are some other clocks, which appeared in Elektor magazines. I've updated the links to those.