Mark
There are lots of guides on how to make your own Ambilight for your TV using Arduino mirocontrolers.
Search for "arduino ambilight" to see the guides and setup needed.
But note that it uses an arduino to analyse the HDMI input into your TV or Monitor (ie when it is used as a monitor connected to your DVD or computer or SKY box). It does not work for TV images that are made directly by the TV (ie using its internal decoder).
SFK