Check out this pico reef tank — built into the empty console of an Xbox 360.
The tank is fully functional and is home to live corals, fish, crabs, snails and shrimp.
It was built to fill as much of the 6" (l) x 8" (d) x 2.5" (w) games console as possible, while still allowing space for filtration.
The tank is lit by a low voltage colour-changing LED strip, and it has an external canister filter containing a sponge and live rock, adapted to 1/4" hose.
Take a look at the video below to get a close-up view.