This app allows you to display PowerPoint presentations on your iPad. Could be great for students to use in a setting such as a science fair or history wax museum.
3DTOAD.com is a library of 3D images that you can rotate and explore. It includes skulls, skeletons, dissections, coral, geology, and even music. These could be great visuals on an Interactive White Board or used on an iPad.
Scribble Press (FREE) is a book creation platform that allows students to both write and illustrate their own stories. Final products can be downloaded to iBooks or ordered as a hard copy.
This is a great article about the evolution of reading. Given the influx of iPads and eReaders into classrooms, the concept of "books" is certainly changing.
This free app combines the best of Panoramio and Google Maps into one app. Think of using this to export the settings of novels, the geography or culture of a historical location, or a virtual field trip.
This is a great site for both streaming and downloading audio books. There are both free as well as paid for options. What's really nice is that you can listen via streaming before deciding whether or not to download the full mp3 file.
This is one app that almost fully replicates the online version. The mobile version of VoiceThread leverages the built-in capabilities of the device to easily create new projects.