[Alessandro Lambardi] had some vacuum flourescent displays that he pulled from junked VCRs. His latest project is an experiment to use one of the VFDs as a headphone amplifier (Wayback Machine Cache). This means he’s trying to use them as vacuum triode amplifiers, aka vacuum tubes. He did get it to work but as he suspected, the output is fairly low power. It may be possible to use this setup as a preamp and build an actual tube amp to use along with it.
Update: Thanks to [Fallen] for mentioning that we’ve covered this concept in the past.