It fell apart when we hit the summer break, but in the early 90s I had been in a campaign that was essentially Quantum Leap, but instead of jumping through time when we solved a problem, we'd jump into another game system. The GM would make new character sheets for us and deal them out randomly after a jump. In the end I think it was done more to satisfy the GMs predilection to getting bored with games, but it was fun enough.