Drum Kit Lite is the free version of Drum Kit, a touch-screen simulator of a six-piece drum kit using real 16-bit sound samples.
The app's interface is a miniature, photo-realistic drum kit, complete with cymbals and pedals, that you just tap to use. The sound has pretty impressive fidelity (best with headphones), and settings let you adjust your kit volume and system volume separately--which helps, for example, if you want to play along with songs from your iPod. Experienced drummers will appreciate nice touches like blending for repeated cymbal taps, while nondrummers can have fun experimenting and trying to pull off drum rolls and rimshots. (Unfortunately, the inevitable--if slightly cynical--placement of a large ad button right next to the kit makes this app a bad choice for entertaining toddlers, who will accidentally buy the full app within seconds.)
Serious drummers will want to buy the full version, with recording capability, multiple kits for different genres, a built-in BPM metronome, and more.