One of my favorite themes is the power of platforms. Provide a standard one can build on, and one can move worlds.
One of the most accidental standards anywhere has been the USB power connector. Not the data channel, the power. A standard plug, 5V, a few amps. Given that standard one can do a large number of interesting things. Too bad the Firewire equivalent didn't catch on; 12V would have been nice.
This store is dedicated to showing what can be done with that platform.