Duolingo allows you to learn up to 35 new languages. It’s available as a website and as a mobile app!
On Freerice.com, students and other users answer questions in their selected categories (ex: geography, foreign languages, English grammar, etc.) in a gamified fashion. When questions are answered correctly, the user receives a score as to how much rice they’ve donated to the World Food Programme. The number is actually a representation of how much the organization receives via ads that will be used to help support the program.
Tinycards lets you make flashcards and then turns them into a review game.