Using an Arduino with Processing I built an OSC remote control.
This project is a weird “bodge” together of various components. The Arduino was running a relay script that let a Processing library control it directly. Within processing there were two apps, one running on my laptop, the other running on an Android tablet. Between the two apps a wireless OSC library was used to send information.
You can learn more about OSC here.
While OSC is designed mainly for sound and midi, I found a way to just use these same signals to control some LEDS.