Backbone.Sync with request queueing.

queue.js

(function(){

  var originalSync = Backbone.sync,
      requestQueue = [];

  var processQueue = function(){
    var req = requestQueue.shift();
    if (!req) return;
    var sync = originalSync.call(Backbone, req.method, req.model, req.options);
    sync.done(processQueue);
    sync.fail(processQueue);
  }

  Backbone.sync = function(method, model, options) {
    if(options.queue === true) {
      requestQueue.push({
        method: method,
        model: model,
        options: options
      });
      if(requestQueue.length === 1){
        processQueue();
      }
    } else {
      originalSync.call(Backbone, method, model, options);
    }
  };

})();