Hi fellow freaks,
As an engineer one of the real treats in larger entertainment shows is of course all the technology. Eurovision was no exception. When we entered the arena everyone was given a Pixmob wristband. They contained 3 RGB leds and an ATtiny44A that were controlled by IR.
The control was insanely fast, the production crew could turn on/off all 11 000 wristbands in an instant. The IR transmitters were directed to different sections of the arena which allowed for sweeping effects too.
Just when the show ended they sent out an impact command. The wristband would then light up for a few seconds after being shaken.
See attachments for photos of the internals of the wristband. Video of the event: http://vimeo.com/66472988
Update: Even better video here.http://www.youtube.com/watch?v=ZtO6pq6qPTU&t=4m47s&hd=1