Haha yeah that's why I had to share it here, seriously fun game. If you've just checked out the free version, the full version is 1000x better, as creative is fun but with crafting, monsters, day/night, limited resources and a dynamic world, the full game can really keep you busy for weeks on end.
The best part is the developer Notch releases a secret update every Friday, sometimes it's something minor like a bug fix or minor gameplay change, but usually it's a new feature, object, tool, etc - meaning that although it's easy to try out most of the game's features pretty quickly, if you're stuck for ideas, just wait a week and make use of the new update.
@Volundr, a little trick, it's half cheating I know, but you'll be really thankful for it if you ever forget to hide your stuff away in a chest and lose all your best items. When you've got a good save, go to Start > Run, type %appdata%, hit enter, it should take you to your AppData/Roaming/ folder, in there you'll see a folder called .minecraft, look inside, in there should be another folder called saves, now go inside, find the world that you're playing on (e.g. World1 or World5), copy the folder out, and if something bad happens in that save, you can delete the folder in AppData/Roaming/.minecraft/saves/ and replace it with the old one (don't just copy the old one over it, as that can mess up the save sometimes)
Kinda nerdy I know, but that's me. I've been messing around with redstone, which allows you to build basic circuits. I've built a 1bit full binary adder, which basically allows you to pull any combination of 3 levers, and it will display the number of levers that are switched on in binary, e.g. if you pull all 3 levers, it displays 11, if you pull any 2, 10, any 1 displays 01, and 0 displays 00. Next up I'm going to try make a 4bit adder.
Pic of the adder (the doors are the output, behind them is gold lit up with torches, and the doors open depending on the combination of levers pulled. I've updated it since this picture and all 3 levers are now in line with each other):