Instead of using the connector from the iPad to the TV, so that what you see on the big screen is only a mirror of what is on the screen of the iPad, you can have a second screen with extra information. There are now applications being sold that will use the extra screen real estate to provide a more immersive experience for the user. The main body of the application residing on the larger screen as you would expect. Starting with games that are selling well on the iTunes AppStore, I expect there will be other apps that manifest themselves to better use the available technology.
One such application that is riding high in the AppStore at the moment is Real Racing 2 HD. The media have picked up on this gaming application that connects up the screen of a HD television for example. You get extra, useful information on your iPad, which also acts as a gamepad motion controller using the gyroscope and accelerometer. The main racing action takes place on the big screen of course, but without it seeming to be superfluous or distracting you, the driver getting more information to give the game more interest.
Photoshop touch applications are being released where the iPad can be used in the same way that you could use a Wacom tablet to control the editing and manipulating of the photo or graphic design. You could be dealing with layers, filters and touching up red eye on the iPad 2. A DJ might be able to control virtual vinyl disks on the iPad while the large screen could be used to visualise what is going on better in the application.
I could see that happening with the software like the FinalCut X where you might be able to move clips and do a lot of the editing of a movie. Depending on how well it is implemented will determine if it gets used for the top applications like Final Cut Pro or if it gravitates to usage in iMovie instead. Garageband would be another candidate for this approach too. The only problem is when the application developers start making applications that have to be used in this way and then not work well enough on the iPad by itself.
All the iOS application developers companies are looking for ways to get products that are that little bit special, in order to stand out from the crowd. We can expect to see major and possible surprising steps forward in the iOD applications world.