NXTManiac wrote in about a new NXT Project titled Marble Madness.
"It's a robotic marble machine that propels marbles around a track, using many different ways of moving the marbles up, down, and around. It was made over the course of 4 days, much of the time figuring outs different ways to make the marbles move around. The final design (many tests and prototypes) includes steps, treads, and slides."
Check it out here.