Today's app for the iPhone (and iPad) is Wikihood. Sure it is just a fancy interface to Wikipedia that does a location specific search and presents all the information found in an easy to use format. As unimpressive as that sounds in practice it works very well. I've found things about the area I live that I never knew. It will use location services or you can search either by typing in a keyword or using a map. Best of all it is free, though if you want an upgraded version it is $4.99. I'm using the free version and am quite pleased with the results.