After watching this guy successfully mine bitcoin on a Game Boy, he revised the online protocol to make link cable multiplayer over the internet possible.
I think this is cool enough for its own topic. I actually started mentally planning to build a pile of these, but when I checked the -More- details, he's selling them for cheaper than I can source the parts. I'm going to finally jump into the online multiplayer gaming world. I'll build a pile of these one night after they arrive and find a way to gift them to the community here.
https://www.youtube.com/watch?v=KtHu693wE9o