Python for iOS supplies a much-needed scratch for those with an itch to write programs for the iPad or iPhone by letting you write software for the device on the device itself. The app provides a familiar interactive interpreter interface for Python programmers plus some extras that make it easy to use, especially on an iPad.
The third button from the left--a green cartoon python--launches the documentation. This is an invaluable resource for quick language research and refreshing your memory about all things Python. Although the docs are hard to read on an iPhone, the type is big enough to easily read on an iPad.