GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
Trivia for Google Chat - Team-building w/ fun quizzes, games right inside Google Chat
Read This Twice - Verified book recommendations from people we look up to
Icebreaker from Range - Start your meeting with 200+ free team-building questions
BookAuthority - BookAuthority collects the most recommended books on business, technology and science - as featured on CNN, Inc and Forbes
meet.atSlack - Team building on Slack