At University, Alexander Zenger and I decided to realise a weatherstation with an [Arduino Microcontroller][arduino]. We wanted to measure temperatur, pressure and humidity. It should be also possible to get every 5 min a value update on an external server.
Our basic idea was to develope a weatherstation which is easy to use with different technologies (Smartphone, Internet, Microcontroller, …). It should also be possible to add new sensors quite easy and adapt the station to your own needs.