This is a cool iPhone app. GeoPedia uses an iPhone's (v1.1.3 and up) positional data to find your approximate location, then return Wikipedia articles related to where you are. So, perhaps you're standing on the corner of Lincoln and Fullerton in Chicago. You'll likely see an article about the Biograph Theatre, the site where famous outlaw John Dillinger was gunned down. It's almost like a personal tour guide no matter where you are.

This is a so-called "Jailbreak" application, so it takes a little work to install. You have to add "http://mazinger.cs.yale.edu/iphone-apps/index.xml" to your Installer.app Source list and install "GeoPedia." The folks over at Into Mobile explain how to get the app for your iPhone.