Looking to rekindle some childhood nostalgia (and make a buck doing so), Mattel has release Rock 'Em Sock 'Em Robots to the Android Market. Rock 'Em Sock 'Em brings all the fun of the classic children's game to the palm of your hand, and adds a few twists. Unfortunately the game doesn't support true multiplayer just yet.
Adding some enhancements to the original button mashing game you know and love, Rock 'Em Sock 'Em includes a gym training feature (your robot can train and level up between fights), defense maneuvers, and health/energy meters, meaning you can't furiously tap the controls for very long before your robot gets tuckered out.
Despite lacking multiplayer functionality, Rock 'Em Sock 'Em definitely seems like a fun time-waster, and at $0.99, it's worth checking out (although the download is a hefty 76MB).