Francisco Sanchez Claria had an interesting problem. He lives about 80 miles away from the lake where he kitesurfs, and the local weather reports aren't accurate enough to predict the optimal weather window in which to go. His solution was to build his own Arduino weather station that he could leave at the lake, and read the weather live from his home computer. Using the data, he can decide whether the weather is good enough to make the two-hour drive.
His Arduino weather station can measure wind speed, gust and direction, temperature, rain, humidity and atmospheric pressure. All the data is read by the Arduino, stored on an SD card, and sent over 3G to his home server. A great deal of thought has gone into how the project can self-manage. It has various fail-safes, checks and watchdogs to monitor the weather station and reset if necessary.
Francisco has detailed the entire build on his website. He carefully explains the various methods, including creating interrupts, watchdogs, de-bouncing, and hiding the box from would-be thieves. It's a pretty good project, and seems robust enough for quite extreme conditions. He's also created a website to show all the data for his fellow kitesurfers to view.