An example for http://codereview.stackexchange.com/questions/38543/node-js-async-callback-hell/38545

gistfile1.js

var mongoose = require('mongoose') 
, Q = require('q')
, Wallet = mongoose.model('Wallet')
, _ = require('underscore')
, bitcoin = require('bitcoin');

function connect(coin) { 
  return new bitcoin.Client({ 
    host: coin.host, 
    port: coin.port, 
    user: coin.user, 
    pass: coin.pass, 
  }); 
}

var wallet = Wallet.find(),
    exec = Q.denodeify(wallet.exec.bind(wallet));

function getServiceBalance(service, userID) {
  var client = connect(service)
  , cmd = Q.denodeify(client.cmd.bind(client))
  , getBalance = Q.denodeify(client.getBalance.bind(client))
  , getAddressesByAccount = Q.denodeify(client.getAddressesByAccount.bind(client));
  
  // We're going to fill this in step by step...
  var result = {
    name: service.name,
    display: service.display,
    abr: service.abr
  };

  return getBalance(userID, 6)
    .then(function (balance) {
      result.balance = balance;
      console.log("Balance:" + balance);
      console.log("User ID: " + userID);
      return getAddressesByAccount(userID);
    })
    .then(function (addresses) {
      console.log("Addresses:", address);

      if (!_.isArray(addresses)) {
        // Throwing errors inside `then` is fine: they will get caught in `catch` below
        throw new Error('Could not get addresses array');
      }

      // For each address, call getreceivedbyaddress and gather results in array
      return Q.all(_.map(addresses, function (address) {
        return cmd('getreceivedbyaddress', address, 6).then(function (received) {
          return [address, received];
        });
      }));
    }).then(function (addressesReceived) {
      result.address = _.object(addressesReceived);
    }).catch(function (err) {
      // Here's the catch method--the *one and only* place all errors propagate to.
      console.log(err);

      result.balance = 'Offline';
      result.address = 'Offline';
    }).thenResolve(result);
}

exports.all = function (req, res) {
  if (!req.isAuthenticated()){
      res.redirect('login');
  } else {
    exec().then(function (services) {
      if (!services) {
        throw new Error('Failed to load any Services');
      }

      var promises = _.map(services, function (service) {
          return getServiceBalance(service, req.user._id);
      });

      return Q.all(promises);
    }).then(function (serviceBalances) {
      req.breadcrumbs('Services', '/services/all');
      res.render('services/index', {
        title: 'Services',
        icon: 'iconfa-cog',
        summary: 'Services information',
        services: serviceBalances,
        path : req.path,
        breadcrumbs: req.breadcrumbs(),
        udata : req.session.user
      });
    }).catch(function (err) {
      console.log('Error:', err);
      // TODO: render an error message?
    }).done();
  }
}