If you've ever seen on of those spectacularly detailed "paintings" done on the iPhone, chances are it was created with this. This is fingerpainting in 2009.
This is an app that started out simple—it was only after a few artists really started leveraging it that it feature set caught up with its potential. Today it's got layers, all manner of brushes, multiple photo importing, and plenty more features you wouldn't expect to see in a mobile image editor.
From the App Developers: Brushes invites you to go beyond the doodle! With several realistic brush styles and the ability to select virtually any paint color, nothing stands between you and your next masterpiece.