"Ohio Art saw his idea at the Nuremberg Toy Fair in 1959. The toy, with its gray screen, red frame and two white knobs that are twisted back and forth to create drawings, was launched in 1960 and became the top seller that holiday season. More than 100 million have been sold worldwide since."

Wow, that must have grossed over a billion in today's dollars. There's a billion-dollar idea for you.