Buddy of mine, Jim "Blackpawn" Scott, created this amazing app for the iPad/iPhone called "Sketch Club." It's a powerful little app that is constantly being updated with new and awesome new features. It's almost like having a $3 travel-size version of Photoshop!
Not only does it sketch and paint, it video records your art in progress and uploads it to Youtube! Here's one I did a while back...
Coolest thing of all... what makes the "Club" part in "Sketch Club"? The people! Sketch Club holds a huge artistic community behind it. People uploading, commenting and sharing each other's galleries. People participating in friendly competitions and art challenges, some involving real prizes!
Get it now for only $2.99. That's less than a Big Mac! Just say'n.