Snarkies
Many political cartoons have a little guy on the bottom corner making snarky comments.   Chris Tombrello and Chad Lupkes suggested that Pat Oliphant may have invented this form [snarky comment guy]. His little penguin was named Punk. Chris thought the insets might be called “cartouches”, but the term doesn’t quite fit. (See http://oldprintgallery.wordpress.com/tag/cartouche/ and http://en.wikipedia.org/wiki/Cartouche_%28disambiguation%29 .)
I propose calling the little cartoon commenters “snarkies.”
I added a snarky to the bottom left of my image about Bill Gates, in response to Elizabeth Hanson’s observation that Gates’ donations to education often supported a corporate takeover of public education.