Arduino Serial USB (Mini Extension Board)
Using the FT232RL, the Arduino Serial USB Board shows up as a com port allowing serial communication to and from the Arduino Stamp or any other serial device.
Arduino is an open-source physical computing platform based on a simple i/o board and a development environment that implements the Processing/Wiring language. Arduino can be used to develop stand-alone interactive objects or can be connected to software on your computer (e.g. Flash, Processing, MaxMSP). The open-source IDE can be downloaded for free (currently for Mac OS X, Windows, and Linux).