Whoops, remembered two more options.
1. Clean rim and pads with a cleaner such as Fantastik or 409.
2. Deflate the tires. Get an emory board, place it lengthwise between one of the brake pads and the rim and then hold the board firmly to the rim. Have someone lightly depress the brakes and then move the wheel (with the board) back and forth. That will remove any glaze that has occured on the surface of the pad.