[BrianG]

Technically, you could charge lipos with a NiMH charger, providing the charger lets you adjust the current on-the-fly. When the battery voltage gets close to 4.2v/cell, just reduce the current in small increments to keep the voltage at that point. Once the current reaches about 1/10th of what you started with, terminate the charge. This is pretty much what all lipo chargers do (which is why I call it "adaptive constant current" instead of a true constant voltage charge). Of course, you'd have to sit there and watch the voltage like a hawk, not to mention the potential for "problems" if you forget...