Cron - Cron Calendar.
Trivia for Google Chat - Team-building w/ fun quizzes, games right inside Google Chat
zcal - zcal is the fastest way to schedule every meeting for Free and make it personal.
Flinkit! - Web-hosted team building games for small and large companies
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Sorry App - Turn outages into opportunities