gistfile1.js

var results = {}; // Stores results of async calculations

var render = function() { /* ... render the page using 'results' ...  */};

var getDatabaseRecords = function(callback) { /* ... async stuff, storing results in 'results' ... */ };
var prepareAssetPaths = function(callback) { /* ... async stuff, storing results in 'results' ... */ };

var tasks = [getDatabaseRecords, prepareAssetPaths],
    params = [
      [],
      [['stylesheet.scss', 'image.png', 'script.js']]
    ],
    times = tasks.length;

tasks.forEach(function(task, index) {
  var _params = params[index] || [];
  _params.push(function() { if(--times === 0) render(); });
  task.apply(this, _params);
});

The async node module makes this kind of behaviour much easier to get at using async.parallel, plus provides a bunch of other useful stuff.