littleBits is an open source library of small electronic components that are already pre-assembled.
The very clever and cool thing about them is that they snap together a bit like LEGO using magnets. This means you don’t need to solder anything, which suits me because I’ve got as much skill with a soldering iron as a gorilla wearing boxing gloves juggling eggs. But it also means the polarity of the circuits is automatically enforced, so you’re not going to burn anything out.
(Via Interaction Design Umeå).