Just spent 10 minutes trying to remember the name of a company that makes power analyzers. Several years ago, I had used a Dranetz power analyzer (can't remember the model number, either, sigh...) to debug a power situation. I have another client with what appears to be an unstable (my guess) AC power feed. Before I ask them to drop some change on a rectifier, it'd be nice to have more knowledge about actual AC power conditions there.
That's where a Dranetz power analyzer comes in handy. Plug it in, config the logging, and walk away. Visit the site in a week and see what it's seen for power sags, surges, irregular waveforms, etc. The ones from the 70's on ebay will probably work fine, and you get skill points for knowing how to use technology older than you are. ;)