Some April Fool's Day Stuff

I'll try to keep a running tab of some of the April Fool's Day stuff I notice. As I write this, I haven't tried to look very much.

The first one that I want to mention is ThinkGeek's catalog. (Tip of the cap to Jennifer Ouellette.)

As usual, there are some special papers on the arXiv, including this one and this one.

Here is another joke arXiv paper. (Tip of the cap to Chad Topaz.)

Here is a roundup of Google's jokes, including the ability to play "Where's Waldo?" on Google Maps.