We've done the RGB led --> Arduino --> Internet trick.

This link will let you change the light color in the steering house of a barge in the Copenhagen harbour owned and run by artists and hackers. http://liljedahl.dk/christian/illutron/picker/

And this one lets you see how much power is currently being used on the barge. http://illutron.appspot.com/PowerGauge.html

Were planning on doing more with this. Throw me an e-mail if anybody wants to play :-)