Dudle - Dudle is an online scheduling application, which is free and open source.
Doodle - Make meetings happen. With Doodle, scheduling becomes quick and easy.
Pulse 24/7 - Booking & scheduling mobile app for service providers
Standuply - Run daily standup meetings and track your metrics in Slack
MakePlans - Online appointment booking - MakePlans
MeetNotes - Increase Productivity with Meeting Notes Tool. More effective minutes, Prepare Agenda, Collaborative Notes & Action Items.