The New Yorker cover I showed you this morning led me on a quest to see more of Jorge Colombo's work, much of which is created on an iPhone. Here's a short video of the motions involved in one such painting. And another video. These are really fun to watch. As my mate is always reminding me, It's not the wand, it's the magician.
There's an interesting short article about Colombo here, and it includes yet another video, this time of the creation of the current New Yorker cover.
If you enjoy drawing on your iPhone or iPad, you should check this guy out. He's a master.