There's an app called "At the Ballpark" from MLB. While it also gives you information about the stadium, the biggest thing is that it's like Four Square. It allows you to check in at the stadium and keeps track of every game you go to. I got it last season and my app says I've been to 9 ballparks and 12 games. I can tell you the scores of all the games and how many times I've seen each team. The Phillies are 0-5 in games I went to, while the Brewers and Dodgers are each 2-1.
It's really cool.