James Gimzewski was at the Tokyo railway station buying a ticket when he saw the clerk at the counter using an abacus. That gave him the idea for his latest project: a nano-abacus, with beads of individual molecules less than a millionth of a millimeter wide. Gimzewski, a physicist at ibm’s research laboratory in Zurich, made the device--which admittedly has no immediate practical application--to demonstrate the sophistication of the techniques he and his colleagues have developed for manipulating individual molecules. Just last year they used a scanning- tunneling microscope to manipulate single molecules at room temperature-- previous work of this sort had to be done at hundreds of degrees below zero. The beads on their abacus are buckyballs--60-atom carbon molecules-- constrained by one-atom-high ridges on a copper sheet. Their tiny abacus does work as an adding machine, albeit rather slowly. It takes about 30 seconds to add two numbers. What’s next on the nano-front? We actually have a pinball machine, Gimzewski says, but we haven’t published that one yet.