There are many tools & apps for ecommerce and magento. From free apps to smart SaaS solutions. Which of them do you use on your own store?
By the way, we've recently selected 21 ecommerce apps & tools that every ecommerce merchant must know. Check it out: http://apter.io/blog/ecommerce-apps-tools-that-every-small-medium-online-store-must-know/