Wolfram Alpha: Math and Science at Your Fingertips
Having quick access to a wealth of knowledge isn't always a good fit for the iPad. After all, the device has a limited amount of memory for local storage, and its mobile processor is designed for email and Web browsing.
The Wolfram Alpha app ($2.99) proves you can do real work on a tablet. Thanks to an extensive back end (Wolfram has thousands of servers processing requests), you can search for answers related to mathematics, thermodynamics, physics, chemistry and much more using a simple search field. There's a browsing component as well; you can use the Examples sidebar to create queries and search the vast research archive.