gistfile1.js

var http    = require('http'),
    mongodb = require('mongodb');

var db = new mongodb.Db('*********************', new mongodb.Server('alex.mongohq.com', 10086, {}));

var inc = 0;

db.open(function (err, db_p) {
  if (err) { throw err; }
  db.authenticate('nodejitsu', '********************', function (err, replies) {
    db.collection('test', function(e, c) {
      function handle(req, res) {
        var value = inc++;
        c.update({ a: inc -1}, {$set: { a: value }}, function() {
          res.end(value.toString());
        });
      }

      c.insert({a: inc}, function(e) {
        http.createServer(handle).listen(8000);
      });
    });
  });
});