Backbone.MeteorCollection, a subclass of Backbone.Collection that updates from a Meteor collection using https://gist.github.com/wearhere/acf71ceba51a2e77c8ec. More info and examples at https://mixmax.com/blog/meteor-and-backbone.

Backbone.MeteorCollection.js

Backbone.MeteorCollection = Backbone.Collection.extend({
  _reactiveQuery: null,
  _waitOn: null,

  /**
   * @param {object} options
   *    @property {ReactiveQuery} reactiveQuery - The query to observe.
   *    @property {Subscription=} waitOn - (Optional) A subscription whose record set corresponds to
   *      _reactiveQuery_. If specified, the collection will wait until the subscription becomes ready
   *      before beginning to observe the query. This avoids emitting 'add' events for every record
   *      in the initial set; rather, the collection will reset itself to the query's result set
   *      (and emit a single 'reset' event) when the subscription becomes ready.
   */
  initialize: function(models, options) {
    if (!(this.model.prototype instanceof Backbone.MeteorModel)) {
      throw 'MeteorCollection models must derive from MeteorModel for syncing to work right.';
    }

    this._reactiveQuery = options.reactiveQuery;
    this._waitOn = options.waitOn;

    if (this._waitOn) {
      this._waitOn.whenReady().then(function() {
        // Once the relevant subscription is ready, reset the collection to the current state of the
        // result set. (We've skipped over the initial 'add' events.)
        this.reset(this._reactiveQuery.fetch());
        this._beginObservingChanges();
      }.bind(this));
    } else {
      this._beginObservingChanges();
    }
  },

  _beginObservingChanges: function() {
    this._reactiveQuery
      .on('added', function(id, fields) {
        var doc = _.extend({ _id: id }, fields);
        // If the collection was not instructed to wait for the relevant subscription to become ready,
        // this will be called for the initial result set. Since that may overlap with the models
        // with which the collection was initialized, we merge the models.
        this.add(doc, { merge: true });
      }, this)
      .on('changed', function(id, fields) {
        var model = this.get(id);
        if (model) {
          var toUnset = _.pick(fields, _.isUndefined);
          model.unset(toUnset);

          var toSet = _.omit(fields, _.isUndefined);
          model.set(toSet);
        }
      }, this)
      .on('removed', function(id) {
        var model = this.get(id);
        if (model) {
          this.remove(model);
        }
      }, this);
  }
});

Backbone.MeteorModel.js

Backbone.MeteorModel = Backbone.Model.extend({
  idAttribute: '_id'
});

This will be renamed/polished/packaged as a full-fledge open-source project soon. In the meantime, this requires:

• Backbone (as you might expect ;)
• the WIP Meteor client at https://gist.github.com/wearhere/acf71ceba51a2e77c8ec