For the full
Rube Goldberg, one could combine a two-speed kick-back hub (Sachs or Bendix) with a Schlumpf Speed Drive crank/bottom bracket, yielding four gears of, say, 40, 54, 66 and 90 inches, with just the single chainwheel and sprocket and without any visible shift mechanisms.
Now that would be rather elegant! Too bad the lack of an actual need and the price of the Schlumpf keeps me from acting on it.
Besides, it'd take some doing to get all the other bits together in something cool looking enough to match such a drivetrain.