Sphere (formerly known as TourWrist) is a free app designed to help you explore the world through your iPad. With Sphere installed on your iPad, you can experience immersive 360 degree panoramic imagery. Open the app, pick a location and zoom to it to view the panoramas. Move your iPad to explore the panoramas.
Sphere could be a great iPad app for your students to use for virtual field trips. On the Sphere blog there is a good list of examples of teachers using Sphere in this manner for lessons in geography, language arts, and science.
Learn more about Sphere in the video below.