Here are a few interesting iPad "content" apps I've run across recently. You should look at these if you are interested in publishing content such as periodicals, graphically rich interactive books, annual reports, etc. to iPads and other tablets.
Mascord Living Spaces: Note the use of 3D image rotation on the house plan pages, as well as pinch and zoom capability on the floor plans.
Fuel Magazine: The landscape orientation is used as a "teaser" for the full content which is displayed in the portrait version.
NCMA Rodin: Interesting navigation menu system at the top of the screen, and a 30 minute high-quality embedded video.
IU Libris: A good example of an "aggregation app" that serves up the various publications produced by the institution. See the IUPUI Alumni Digital Magazine in the app for an interesting navigation system.
AnimalABCLite: Note the "flip" animation on each page. This is done with an HTML5 animation "overlay".
Our Choice: The iPad version of a book by Al Gore. Created by pushpoppress. You've got to check this out as an example of a highly interactive book. Lots of interactive charts and illustrations, nice image treatments and an interesting interface. According to the web site, it was "two years in the making!" so obviously not inexpensive to develop.