One hundred humanoid robots performed a synchronized dance routine in Tokyo on Monday. Each of the one hundred 'Robi' robots weighs just 2.2 pounds and stands just a little over a foot tall. The '100 Robi' project is the brainchild of Tomotaka Takahashi of Tokyo University. The synchronized dance lasted three minutes and went off without a hitch. What made the project so uniquely challenging, Takahashi said, was designing a robot that could be produced in large numbers at a low cost. Each 'Robi' robot costs around $1,500.