Google is celebrating the 180th birthday of John Venn, creator of the Venn diagram, with a special doodle on its front page. The interactive doodle allows you to choose from ten subjects in order to find the correlation between them. Choosing "sea life" and "has wings," for example, will bring up a cutesy illustration of a flying fish. It's a neat illustration of what a Venn diagram is, even if it doesn't quite cover the breadth of the diagrams' uses. It'll be up on Google.com for the rest of the day, after which you can check it out at Google's Doodle archive.