I use this one which is specific for Ember: https://github.com/jamesarosen/ember-i18n
It adds a 't' handlebars helper :
{{t main.offers countBinding="offers.length"}}
It supports plurals (via CDLR.js) and is not limited to handlebars thanks to Em.I18n.TranslateableProperties
mixin, which allows property translation via a convention on any Ember Object.