In order to add custom ejs filters to a SailsJS application you could add them to the express locals variable.

You need to modify your bootstrap.js file:

module.exports.bootstrap = function(cb) {
    var locals = {
        siteTitle: 'LinkPin Pow',
        filters: {
            getTagLabels: function(tags){
                return (tags || []).map(function(t){
                    return t.label;
                }).join(', ');
            }
        }
    }
    sails.util._.extend(sails.hooks.http.app.locals, locals);
  // It's very important to trigger this callback method when you are finished
  // with the bootstrap!  (otherwise your server will never lift, since it's waiting on the bootstrap)
  cb();
};

Then, in your view, you should call it as follows:

<%=: link.tags | getTagLabels %>