WallSmart by Jonas Enqvist is a wall paint that can change colour through the push of a button. (See http://donebyme.com/work/wallsmart/). A prototype will be present at the Nano Supermarket (http://www.nextnature.net/events/nano-supermarket/)
The prototype consists of a paint bucket with RGB LEDs that can change colour. This video shows the communication between the WallSmart App running on an Android mobile device, and the RGB leds connected to an Arduino. A Rayson BTM-110 Bluetooth module converts the Bluetooth serial commands to RS232 (serial) signals.
The colour wheel is based on the OI Color Picker (http://www.openintents.org/en/colorpicker)