Two that stuck out for me were; feminism (there are more women involved than thought & some advice on how to get more) and Open farming (the open source tractor in action video is rather cool)

The Qi Hardware folks seem to have a solution searching for a problem, but the hardware itself is very cool tech. The FAQ provides a good overview.

I also learnt of the Touch Book. An ARM based netbook with huge bttery life, detachable keyboard and touch screen.

The saturday night conversation about maths (and mutilple infinities!) ensured a complete fun weekend.