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.
PlayPlay.io - Chess and Ping Pong tracking in Slack
Mondly - Learn 33 languages in 500 bite-size lessons and 14 conversational modules.
Pinpon - The ping pong bot for Slack
Lingvo TV - Learn languages while watching movies on Netflix.
Ranked.Fun - An online leaderboard with your friends for your favorite games (Ping Pong, Foosball, Smash Ultimate, Chess, etc.)