Meetsy
Create your own polls - Terminplaner 4.1
Easy!Appointments – Open Source Appointment Scheduler
Cal.com | Open Scheduling Infrastructure
PeachPay - Monetize your Content
CoreUM - The Ultimate Meeting Application
Polymail — Email Tracking, Templates, Send Later, and Calendar Integration
Calendly - Scheduling appointments and meetings is super easy with Calendly.
Meetin.gs - Free, Easy and Better Online Meeting Organizer
World Time Buddy - Ridiculously easy world time and meetings across time zones!