Adobe released Adobe Ideas for iPhone perhaps as recently as last week.  I have done five pieces in it thus far.  The first three were of other people and then I got jealous so I did a self-portrait as piece number four.

Adobe Ideas takes your finger-brush-strokes and turns them into smooth vector representations. The image is then emailed as a PDF.  As such, these pictures technically merit a footnote since although they were 100% designed on the iPhone I actually rendered them hi-res on my computer to create the image you see.  The upside is that I could render it billboard size with no loss of quality.