MediaBistro appears to have discovered a good app for all the doodlers out there. Qvik Sketch Pro is a simple app that costs only $.99 and provides several brushes, including a few augmented ones.
The augmentation brushes included are:
Apparently, you can change the color and size for each brush as well as adjust a few things by changing the speed of your fingers. The simplicity of the app allows for elegant paintings made from just a few swipes. MediaBistro thinks that the app is fantastic but could use a simple photo overlay picture to start tracing for a new painting.