Simple Poll - The easiest way to create polls in Slack
Poll Everywhere Competitions - A point-based trivia contest with a live leaderboard.
iPoll.app - Create instant polls and forms with in slack!
QuizBreaker - A fun online quiz game for teams to get to know each other
doopoll - Create live, instant, editable polls effortlessly
You're Eliminated - HQ spin-off game where the wrong answer is the right answer