In the video above, artist Yoshitoshi Abe uses LiveSketch HD [$0.99] to sketch one of his characters named Ain. Yoshitoshi's normal medium is pencil and paper, but you can see that the detail he achieves in the sketch on the iPad is almost in parity with his pencil sketches.
What's even more impressive is that he does the sketch in under four minutes and uses only one hand. As you can see in the video, his other hand is busy holding his iPhone 3GS, which he is using to record his creation. Ah, when talent and technology meet.