A few guys from different corners of the world have gotten together and created the Lightpack – an affordable ambient backlighting system, much like Philips’ Ambilight.
The drawback compared to Philips’ system, is that the Lightpack requires software to be installed on a computer to run.
The FAQ states that they are working to get support for up to two Lightpacks in sync via the included Prismatik software, to enable multi-display and better large (50″+) diagonal displays support.
Personally, I think it’s both fairly cheap and looks like a neat package. Since I’ve been waiting for something like this for my PC for a while, I’m now officially a backer!