Untested queue

q.js

var q = (function() {

    var me = this,
        _callbacks = [],
        _index = -1,
        _nonePending = true;

    me.then = function(callback) {
        // Add this to the queue
        _callbacks.push(callback);
    };

    me.next = function() {
        // See if there is another one to execute
        if (_index < _callbacks.length) {
            // Increment index
            _index++;
            _nonePending = false;
            _callbacks[_index](me);
        }
        else {
            _nonePending = true;
        }
    };

    me.start = function() {
        if (_nonePending) {
            me.next();
        }
    };

    return me;

})();