I own the Comic Touch app and it has somewhat of a "face melt" feature where you can "Bulge, Dent, Squeeze, Stretch, and add Light" to your photos. In addition to this feature you also can add cool comic captions, etc. to your iPhone images and then easily upload or email them wherever you see fit.
The Comic Touch app is only $1 more than the Face Melter app so you might want to consider your options there. I was very happy with the $3 I spent on Comic Touch, it's a really cool little app and I use it more than I really anticipated.