Duolingo has been the receiver of many accolades both for the online site and the app versions. It takes a gamified, easy-to-use approach to learning languages -- with fantastic results. If you've ever dreamed of learning a second language (or third, or fourth) Duolingo might just be the place to start. The best part about it is that every aspect of the service is completely free. Free of subscriptions, free of ads, free of app costs. They were able to pull this off by essentially turning their user base into a giant crowd-sourced web translation service. While you use Duolingo and learn the language of your choice, you will be unwittingly helping to translate text from around the web, a service that is actually worth a pretty penny to those looking for real, human translation.