I wanted to see how quickly I could code a chat server with sockets. I've never used node.js before and this took me about 2 hours to figure out completely.
Obviously it's still far from perfect, but it gives you some idea as to how parts of socket.io, node.js and express work I suppose.
cd into the directory and type:
node app.js
accessible @ localhost:3000
If you want to get this running with clients connecting from other hosts you will need to change
var socket = io.connect('http://localhost');
in public/javascripts/script.js to the address of your server. There's probably an easy way I could code around this, but what the hell.