If you have a bunch of jars laying about, or looking for an avant-garde form of lighting then consider the following project by Instructables member funelab. They've fitted RGB LEDs inside jars with a simple mount, all of which are controlled via an Arduino-compatible circuit.
The system can be battery operated for convenience, however a licensed electrician could help with wiring the controller to the main circuit. Once completed you can use your imagination to create vairous lighting effects, or create an interactive display based on data from a temperature, light or sound sensor. In the meanwhile, a montage of creation and operation is shown in the following video:
If you're interested in experimenting with RGB LEDs as demonstrated above, we're offering large and bright 8mm diameter RGB LEDs:
They're in the common-anode format and look great when lit up. Ideal for colour-mixing and creating displays of all sorts. For more information and to order, visit the product page.