For the advanced player, Xyloba Orchestra, an ingenious musical marble run from Switzerland, has 96 pieces for creative buliding and musical play.  Using wooden blocks and ramps in combination with xylophone keys, players can use different length ramps allow for 1/2 notes, 1/4 notes and 1/8 notes, so it's not only a marble run, but allows players to create specific melodies.  96 pieces.

Visit Xyloba's home site in Switzerland for additional images and information.  Ages 3 and up.  CAUTION:  Marbles can represent a choking hazard to very young children.