Movable Python is a portable distribution of Python for Windows capable of running of a USB stick.
It includes both the pre-built distributions of Python, plus the scripts required to build the distributions. Distributions are built with py2exe.
As the distributions are isolated from any installed version of Python, Movable Python can be used for testing code with different versions of Python. The Movable Python interpreter behaves as much as possible like the standard Python interpreter.
The standard distribution includes the full standard library and the PythonWin and IDLE IDEs - it makes a portable development environment.
A modified version of Movable Python could be used to create standalone applications without needing to bundle (and re-bundle) with py2exe.