I like to permanently jumper them. Cut a narrow strip of the doublestick foam right down the center of the back, and peel it off. You have room to solder two wires between the power busses, and it still lies flat. Screw it back to the aluminum plate, or put a piece of packing tape over it so the wires can't stick out.
If you really want to get crazy with multiple voltage rails, you could buy extra breadboards and take out the power rails and stack them together. So you have multiple rails top and bottom? Seems like all the good boards have removable power rails.