Knockman is a cute, little plastic knick-knack that pounds its head with its fist. Once wound up by pumping the other arm, Knockman's fist starts pounding away. If you position another Knockman near by, you can even move the fist to pound on the second Knockman's head. The smiles on their faces make them look happy while they are doing this!
Knockman has other buddies too. Kerotama is wound using the spring on top of his head, and a ball circles around him, creating a whoosh sound. ChaCha is wound the same way, although he has a mini-symbol that pounds when let go. Perhaps the coolest one is Pololon. His arm slides against three guitar-like strings that produce a cool sound. You can even tune the strings by opening an enclosure at the top of his head!
There's also another one who's name I'm almost afraid to say: Colon. He jiggles as chimes inside of him move back and forth creating a wind-chime sound. More info on these products can be found at http://www.knockman.net.