PowerGadgets' out-map cmdlet allows you to create your own "maps" to visually represent data. I've blogged before about how I used a view of a World map to represent some data.
So here you have a very basic traffic light gadget:
Unfortunately, using a true circle is not supported, so creating a square/rectangular light is the path I took.
The possibilities of using PowerGadgets for visualizing custom data are almost limitless. Check out this out-map view of an airplane!.