Yo Dawg we heard you liked async

gistfile1.js

var interator_func = function(array_element, callback) {

  wraps_waterfall('foo', function (err, top_level_data)

      async.waterfall([

        function(wf_callback) {
            // do work
            wf_callback(null, data);
        },

        function(data, wf_callback) {
            // call an async function with work
            an_async_function(data, function(results) {
                wf_callback(results, data);
          });
        },

        function(results, data, wf_callback) {
            // more work
            wf_callback(null, data);

            // reference a top level variable
            data.blah = top_level_data;
        }

      ], function(err, data) {
        // final work
        callback();
      });

  });

};

async.forEach(an_array, interator_func, function(err) {
    // interator_func has now been called on every
    // element in an_array.
});