Philips Hue Lights
These are ridiculously-expensive lightbulbs, but they sure are fun. The system that Philips put together actually works well and they’ve allowed for an open-ecosystem of apps to be build around the bulbs.
I got these strategically aimed around the house. I can easily set the mood for movies or different types of music. I can turn lights on and off while away, have lights turn off at a certain time, have the house light up a certain way right after sunset, or even turn the lights on and off with my Pebble watch. I love it.