Major League Baseball's At Bat for the iPhone and iPod Touch is one of my all-time favorites. I've sung its praises before, so I'll spare you the details. Just know that At Bat brings real-time stats, streaming audio and video of pro baseball games to your iPhone and iPod touch. Last month they added in-app purchases that let you grab a live game for $0.99US.
Now that the post season has begun, they've improved the app again. You can watch live post season games through the World Series with 7 camera angles to choose from. Or you can watch a split screen of four camera angles simultaneously. Admittedly, those four screens are tiny on an iPhone's screen but it's still fun. Switching from one angle to another is quick and simple.
At Bat costs $9.99 per season and is completely worth it. I use it every day to watch games, get stats, read stories, check standings and more. There's a free "lite" version as well [iTunes link], which provides real-time scores and schedules.