For the first useful thing I ever built in node, I hacked together this reverse proxy script so that I could fiddle with front-end code on a remote website more easily. It sits between your computer and the remote site, checking first for files in a folder you specify, then trying a GET request against the site.

reverse-proxy.js

var http = require('http'),
	path = require('path'),
	fs = require('fs'),
	localPath = "/PATH/TO/LOCAL/FOLDER/",
	remoteServer = { host: 'www.example.com',
					 port: 80
	},
	mimeTypes = { 'js' : 'text/javascript',
				  'css' : 'text/css',
				  'html' : 'text/html',
				  'png': 'image/png' },
	queryStringRE = /\?.*$/;

http.createServer(function (req, res) {
	var localfile = path.normalize(localPath + req.url.replace(queryStringRE, ''));
	path.exists(localfile, function (exists) {
		if (exists && localfile != localPath) {
			console.log('Serving local file: ' + localfile);
			fs.readFile(localfile, function (err, data) {
				res.writeHead("200", {'Content-Type': mimeTypes[path.extname(req.url)]});
				res.write(data);
				res.end();
			});
		} else {
			console.log('No local file: ' + path.normalize(localPath + req.url) + ', serving remote.');
			remoteServer.path = req.url;
			remoteServer.method = req.method;
			http.request(remoteServer, function(remoteRes) {
				res.writeHead(remoteRes.statusCode,  remoteRes.headers);
				remoteRes.on("data", function (chunk) {
					res.write(chunk);
				}).on("end", function () {
					res.end();
				});
			}).on('error', function(e) {
			  console.log("Got error: " + e.message);
			}).end();
		}
	});


}).listen(8080, '127.0.0.1');

console.log('Server running at http://127.0.0.1:8080/');