From Xada Technology:
Weather Now communicates with a serial data-logger-equipped Vantage Pro weather console. It will show temperature, humidity, wind speed, forecast, and the other info on-screen, via a summary window, a detailed view, or temperature-only in a small floating window. Data can be logged for historical analysis. It is also AppleScript enabled so you can get weather data in to (your IM status, home automation decision making, overlay on your webcam, etc).