So I'm relatively new to Arduino having only made a couple of things so far.
I finally finished my backlight project this week which I use to add a bit of immersion to films/games:
It uses an Arduino Nano, an Adafruit Electret Microphone Amplifier (sound sensor), some RasPiO LED rings and a few other bits.
Full details are on my blog: Arduino Backlight Project | Average Maker
I also made a short video of it on YouTube: Arduino Backlight Project - YouTube