Tapgic Technology Limited has Drum On (iTunes Link) for the iPad in the iTunes App Store for FREE (regularly $1.99) for a limited time.

Drum On is designed for both pro drummers and other musicians. It turns your iPad into an advanced drum pad just like a real electronic drum pad, so you can Jam with your band anywhere just with your iPad.

Drum On is developed with customized high-fidelity audio playback system and loaded with many great Drum kits and Sounds. All sounds are over 16bit/44.1kHz to 24bit/48kHz PCM quality which are produced in Tapgic Music Studio.