Check out these web sites that show artwork created using the iPhone App Brushes.
“Brushes is a natural media painting application designed from scratch for the iPhone and iPod touch. Featuring an advanced color picker, several realistic brushes, multiple layers, extreme zooming, and a simple yet deep interface, it is a powerful tool for creating original artwork on your mobile device. Brushes allows you to choose any color (including transparency) using the hue/saturation color wheel. With a generous level of undo and redo you never need to worry about making a mistake or backing up too far. Brushes records all of your actions when painting. These actions are stored in a .brushes file which you can download directly from your iPhone or iPod touch via Brushes’ built-in web server.” – Brushes website
Image from iartmobile.com