One of the new iPhone apps that was demoed at the iPhoneLaunchParty last night was bChamp by Monodomo. bChamp is a beat-boxing application that allows you to use your iPhone as a beat-boxing device. It's hard to describe so we'll start with this developer video that shows you the basics:
The pitch of the sounds can also be changed by moving your finger on the screen. Steve Wozniak was at the iPhone Launch Party and tried his hand at bChamp:
bChamp is available in the App Store. Another video shows the actual demo at the party.
App Store Link: bChamp, $0.99