Recommended
Reactive LED Coffee Table - Arduino
Why people recommend it
Shown as an eye-catching Arduino demonstration of LEDs reacting to touch and movement, and cited as a practical example of an infrared sensor array.
Watch for: Inspiration more than a build guide
In their words
Here is a video (and here) that shows this in practice.
aaa on arduino.stackexchange.com, Nov 2017. CC BY-SA.