Oh right! My Mom used to use an electric "skillet" all the time. That might work really well, although it wasn't terribly deep, maybe only 2.5-3" deep. I seem to recall an episode of good eats about these electric skillets and that they're pretty accurate.

I was just thinking it might be a nifty way to make stove top custards. Get the water to around 160' which is where you want the custard to end up at. Then you never have to worry about it over-cooking.