VideoPano for the Iphone
Taking panoramic shots is often difficult mainly in judging the alignment and lighting. VideoPano for the iPhone uses a super easy and innovative way to take great panoramic shots in an instant. Basically you take a video of the panorama you want like below.
Here are a few other examples.
And this one is in the train I am currently travelling on.
If there is a panoramic app you want to buy I would recommend VideoPano in the AppStore. It's super easy and the results are beautiful.