Alan Pullen is currently working on a weather station project which will bring together a Pi with an Arduino to take readings and display them onto a Raspberry Pi touchscreen. He wants to measure temperature, pressure, humidity, rainfall and, very excitingly lightning strikes! The interface will be written in Kivy which has previously been shown to be a great way of doing touchscreen control panels. He wrote about the start of his project on his blog and he is maintaining a project page here.