Lots of cool ideas here. If you get one working please post as I might want to build one myself. You might consider having the resolution to measure short term power outages (sub 1 second). Around here our service provider doesn't consider anything less than 30 seconds a power outage. That is fine, but I happen to believe that any service disruption is a problem. If it makes my computer die and my stereo loose it's presets its a problem.
At the business I worked at this summer we had a flywheel that provided instant transitional power for our test equipment to cover short outages until the generator fired up. The flywheel has a counter that displays the number of times it has been activated. Everyone is always surprised to see how often it runs.