I’m currently attending Chaos Communication Camp 2011 in Finowfurt near Berlin.
Apart from the cool location within an used-to-be military airport open-air aviation museum, the coolest thing so far definitely is the electronic badge handed out at the entrance: The r0ket, an ARMv7 micro controller with back-lit LED-display, several LEDs (of which one is also used as a light sensor to determine whether it’s night and the badge display needs back light), a multi-way jog, a rechargeable battery and some extension-connectors.
The badge also features mesh-networking capabilities, although the firmware for that does not seem very stable or reliably usable at the moment. I will definitely be keeping this tool toy – there’s no better name-tag than this, I guess.