Finally joined the ranks of Arduino community and got my first project up and running :). Inspired by many Ambilight implementations, I also wanted to make one, but with a little twist. I wanted to add lighting to our living room TV, but I don't have a computer media center connected to it - most of my video inputs come from xbox or regular TV cable box. Since HDMI pass-through would be a bit hard to do, I've opted for controlling my setup with a laptop and a webcam, which captures TV screen, samples colors around edges and sends them to Arduino.
Hardware is nothing special, with no custom components. It is simply Arduino Uno, with ShiftBrite Shield and 16 daisy-chained ShiftBrite LEDs.
Source code for sketch and controlling app is available at https://github.com/underclouds/GlowLight
Demo/Rainbow mode: http://www.youtube.com/watch?v=63lvGv4p_Qg
Movie mode: http://www.youtube.com/watch?v=Sn1R9-R6RP4
One problem I've encountered is that power supply I've got (http://macetech.com/store/index.php?main_page=product_info&cPath=2&products_id=2) seems to be having troubles driving all 16 LEDs at full brightness, so it's running at only 40% at the moment. In the next steps, also planning to add bluetooth and offload screen capture and processing to a smartphone.