LED sheep art.

art? I don't know, but its still pretty sweet.

Distance Sensor

This guy was building a robot and wanted a way that others could visually tell they were to close.  He hooked a distance sensor up to an arduino and LED and went to town.  Green means you are a safe distance away, yellow is a cautionary warning, a red signals the robot to move away .  Here is a short youtube video of him testing it.