App-Date: History Here
I'm a big history geek, so when a coworker told me about the History Here app, I had to grab it.
Released by The History Channel (they just call themselves "History" now, though, right?), it uses Google Maps to show you historical sites near you. Near me, Western Ave in Augusta, it shows me the Maine State House, The Blaine House, Fort Western. In the Waterville area, we have Fort Halifax, and in Madison there's the Old Point Site.
There are also guided tours and, if you just wanna' learn some history and you don't care where it comes from, there's a "Surprise Me" option.
Grab it from Google Play or AppStore