One of the reasons I have been distracted from my Prusa over the past couple of weeks is Quick2Wire.com.
A group of us have got together and started to build a series of add-on boards for the Raspberry PI. The first board will allow you to connect the PI to the outside world and will provide an API that can drive the connected devices. It is early days yet, but I can see several projects evolving out of this.
Why not checkout Quick2wire.com. Sign up for the mailing list and we will keep you posted on our progress.