Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.
Cards against Humanity - A party game for horrible people.
Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.
PlayPlay.io - Chess and Ping Pong tracking in Slack
Lingvo TV - Learn languages while watching movies on Netflix.
PongUp - The ping pong leaderboard for awesome offices