I dont use it that often but the basic Graffiti package is pretty cool if quite the test of agility. Can't zoom in. Can't really erase. Its like a very, very basic version of photoshop. You have to play with the layering of colour and opacity. Good for a doodle anyway, and at the end you can click replay and watch how your work came to be.
Some of my fellow facebookers have it down to perfection and are well worth visiting the various groups on facebook to checkout.
But here in no particular order are some of mine