Here's a novel project. It's a mini desktop wind direction indicator, and the first 'fun' Arduino weather monitor we've seen. Using the Yahoo Weather API and the Processing app, it pivots a windsock using a servo in the correct direction of the wind in any given city.
The servo's position has been measured as accurate by measuring with a table compass and updates every 10 seconds. It could be useful for pilots or in extreme sports to quickly check if it's worth travelling today.
It uses Onformative's YahooWeather library for Processing. This API has loads of cool features, and looks pretty easy to implement. Maybe the next update could change the vertical angle of the windsock to show wind speed? Or have a pseudo-thermometer? Or fire a water cannon if it's raining?