[Dog Gone]

Check this out!

http://mail.google.com/mail/help/paper/more.html

[Atlas Sneezed]

http://www.google.com/tisp/install.html

NPR used to do some pretty good ones. They had the right shtick, where the story started serious, and added increasing degrees of absurdity, ending with emphasizing the date, without actually saying "April Fool!"

http://www.npr.org/templates/story/story.php?storyId=9210663