gistfile1.js

if (Meteor.isServer) {
  var path = __meteor_bootstrap__.require('path');
  var MongoDB = __meteor_bootstrap__.require('mongodb');
  var Future = __meteor_bootstrap__.require(path.join('fibers', 'future'));

  var Books = new Meteor.Collection('Books');

  Meteor.startup(function () {
    Books.aggregate = function(pipeline) {
      var self = this;

      var future = new Future;
      self.find()._mongo.db.createCollection(self._name, function (err, collection) {
        if (err) {
          future.throw(err);
          return;
        }
        collection.aggregate(pipeline, function(err, result) {
          if (err) {
            future.throw(err);
            return;
          }
          future.ret([true, result])
        });
      });
      var result = future.wait();
      if (!result[0]) {
        throw result[1];
      }
      return result[1];
    };

  });
  Meteor.methods({
    myAggregationMethod: function() {
      return Books.aggregate([ { $group: { _id: null,  total: { $sum: "$counter"} } } ] );
    }
  });

}