Minecraft's red stone allows you to do a lot of very, very clever things - like build a functioning hard drive. No, this isn't a joke.
Minecraft has a lot more scope than surface explorations reveal. With redstone, you can build switches and simple logic circuits, and with that, well - you can make anything.
That's not to say it's easy, by any means. You need a good grasp of the fundamental principles you're exploiting, a grand vision, and a lot of patience. I suspect Imgurian smellytring has these qualities in droves, looking at this gallery of images.
What you're looking at is a functional 1KB hard drive. "What in the hell?" You may exclaim. "How? Why?" Here's an explanation culled from the excellent commentary provided with the gallery:
"Redstone signals can pass through solid (opaque) blocks, but not clear blocks.
"To store data on a computer, you must use binary code. Binary code is basically a way of storing data using only 1s and 0s. On my hard drive I use solid blocks to store a 1 and clear blocks to store a 0.
"I use a LOT of pistons to push a bunch of blocks around in a loop. By switching between solid and clear blocks in this loop, I can store data. My hard drive has a spin speed of 1 byte per 8 redstone ticks."
A command room gives the player the ability to control the hard drive. If you're interested in programming or basic computer architecture, figuring out precisely how this works wouldn't be a bad way to start.
If you haven't played Minecraft yet (what_ it's available on Mac, PC, PS3 and Xbox 360, with PS4, Vita and Xbox One versions due soon.