We've got a Christmas tree ornament that has a changing pattern of lights inside. I took it apart to find that there is a single LED connected to the battery with a switch. That's it - must be some circuitry built in to the LED but it's clear and just look like a normal one - where can these be bought?
Never mind, just found it here:
Wonder how they work, though?
You will see a tiny black dot inside the LED, that is the chip controlling it.
Spandit there is a pdf explainig the operation of these here -
Astonishing really (and that's from someone writing this on an iPhone)