callbackhell example from http://tjholowaychuk.com/post/5396719370/node-recap

callback-hell.js

var News = db.model('News');
app.get('/dashboard', function (req, res, next) {
  req.user.getLikes(function(err, likes){
    if (err) return next(err);
    News.getLatest(function(err, news){
      if (err) return next(err);
      res.render('dashboard', { likes: likes, latestNews: news });
    });
  });
});