Setting foot on a Harry Potter-themed Minecraft server is definitely the nerdiest thing I've done in some time, but if you're a fan of either beautiful architecture or Rowling's tales of pubescent wizardy, then I'd recommend you give Pottercraft a look.
It's a very impressive piece of work, not least because it's so big, but also because you'll recognise it all from the films or the books or your nerdy imagination. There's the Chamber of Secrets, the great Wizard Chess board, the Gryffindor common room hidden behind a painting and that tree that flung Hermione about.
The neatest feature, though, is the house sorting system, where you plummet down a hole and find yourself in a small labyrinth marked with signs asking you about what you want from life. Following these signs through tunnels and down more pits eventually leads you to a final sign that declaims your house, based on a (not very) intimate analysis of your thought process.
"RAVENCLAW!" said mine, which made me much more satisfied than any 32-year-old man should be about such things. If I'd wanted, I could've asked an admin to pin my house next to my user name. The server is full of people called things like harrypotter529, but at present there isn't much to do except explore and flick a few switches. I smell a roleplay server in the making.
Still, it's fantastic to explore and absolutely worth checking out for all its architectural inspiration. The server address is pottercraft.simpleno.de and you can find out more about it on the Minecraft forums here.