Kentaro Toyama is very proud of this device--a racquetball suspended in a wooden frame by rubber bands--a result of his computer science research at Yale. Toyama, a graduate student, calls the object of his seemingly unjustified pride a surfball. What does it do? The surfball is essentially a computer mouse that could control the motion of, say, a robotic arm moving in three dimensions. A video camera tracks the ball by following two colored dots on it and feeds that information into a computer. The computer calculates the exact motion of the ball and scales up the movements for a robotic arm. Compared with a mouse, or even a joystick, the surfball can move the objects it controls through a greater range of motions. Says Toyama, You can move it forward and back, shift it left to right, up and down, and then rotate around all of those axes.