OSCirrus

OSCirrus is an expandable, open source software weather station built on inexpensive hardware and weather sensors. Version 1.0 consists of a wind vane (direction) and anemometer (wind speed) from Fascinating Electronics, an AVR MT 128 microcontroller embedded platform manufactured by Olimex and sold by Spark Fun Electronics in the US, and some middleware for importing the controller data and exporting the weather data to an XML package for delivering over the web. Here are a couple of glimpses of it:

http://oscirrus.see-do.org/