The ABC Player app was one of the first apps made for the iPad. This app allows you to watch most of ABC's shows whenever you want. The app also saves your spot if you need to stop to do something else for awhile. Much like Hulu there are commercials in the shows but most of the time there are only two and they last about a minute total. You can also check ABC's schedule to see when your favorite shows come are on.
Until recently this was one of the few if not only app that allowed you to watch a television channel without some sort of service (like signing in with a cable plan or a pay service like Netflix or Hulu Plus) I'm sure the fact that Steve Jobs had a lot of pull at ABC really helped to make this app happen. NBC now also has a simular app and hopefully the others will follow ABC's lead. The app is free and great if you like some of the shows on ABC.