If you can't keep your hands off your nephew's Mr. Potato Head, you might enjoy playing with monoface from the PR firm mono (lowercase "m" intentional). It's a Flash-based application that allows you to mix and match various facial features from a number of real-life people to make interesting and sometimes hilarious results. The blending between the various features is mostly fantastic, with only the occasional face that ends up looking like a real cut-and-paste job.

It's not really clear what this is good for, other than wasting time - but since that's the point of this post, waste away!