I have Mosquitto MQTT setup on a RaspBerry Pi 2. This Pi is also the WiFi AP for many ESP8266-enabled devices/sensors. It also has HomeGenie installed.
I've seen the Philips Hue widget/program, but I am thinking there must be a more generic configuration for something like an RGB LED? I don't mind colors being specified by HSB values. I do like the color selector and would like something similar for a generic RGB LED.