I have an early digital video camera with a genius design. It came with a custom rechargeable cell in the battery compartment. But the compartment _also_ supports regular AA batteries.
Most petzl headlamps are setup this way for a small lipo pack or 3 aaa's. It's great
Brother label printers used to support this up until a couple of years ago at least but sadly the most recent models have stopped having the AA compatibility.
Absolutely the best of both worlds. You can find a shop selling AA everywhere in a pinch and keeping a few in the camera bag is easy too.