pylibftdi is a simple library interacting with FTDI devices to provide serial and parallel IO from Python.
The two main use cases it serves are:
FTDI (http://www.ftdichip.com) create devices (chipsets, modules, cables etc) to interface devices to the USB port of your computer.
libftdi (http://www.intra2net.com/en/developer/libftdi/) is an open source driver to communicate with these devices, and runs on top of libusb. It works on Windows, Linux, and Mac OS X, and likely other systems too.
pylibftdi is a pure Python module which interfaces (via ctypes) to libftdi, exposing a simple file-like API to connected devices. It supports serial and parallel IO in a straight-forward way, and aims to be one of the simplest ways of interacting with the world outside your PC.