There's this page that I saw with some pretty great art. (imo) They can be thought provoking, sad, and/or funny. This is where it's from: http://capu.pl/node/271
Here are my favorites of them.
My favorites pretty much don't include the ones that have a message against something, or the kind of sad ones. I like absurdity more than art about world issues. There are many more of each category on the site, though.