I'll be honest with you. I don't understand Minecraft. I can mine rocks and craft a sword, but start to talk about redstone and switches and my eyes glaze over. One very gifted individual has gone above and beyond anything else I've seen created in the open-world crafting sim, though, and put together a fully functional hard drive with a storage capacity of 1KB.
These images come to us via Imgur via Reddit via 'smellystring', the scholar who actually put the system together. For the entire set of images, and a proper explanation of how it all works, check out the album.
The idea behind it is simple enough -- in each memory register, a two-position slider has both a glass block and a solid block. Redstone signals in Minecraft can only pass through solid blocks, so switching between the two blocks gives two different states -- so a solid block redstone circuit can represent a 1 in binary code and a clear block redstone circuit represents a 0. In that way, binary code can be written and data can be stored. The rest is just repetition, really.
These redstone hard drives aren't especially new, but this one is both (relatively) high density and looks pretty damn amazing. There's a little more discussion on the /r/Minecraft Reddit thread, which as a bonus includes some excellent Isaac Asimov references. As for the hard drive -- I sort of get it. I think. [Reddit]