Here's a small gallery of work by Heartfield who left a huge though often subterranean influence on leftist graphics. Much of this is still quite striking and unusual for much topical commentary is still quite understandable. (Just grab some editorial cartoons from a few years back to see how quickly this stuff can date.) There was a really amazing catalog from a MOMA exhibit in the early 90s that showed a lot of Heartfield's other work such as posters and dust jackets.