Calendly - Say goodbye to phone and email tag for finding the perfect meeting time with Calendly. It's 100% free, super easy to use and you'll love our customer service.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Meetsy - Invite friends for your events and gather everybody's photos
Dotcal - Personalized booking pages for absolutely everyone
Cron - Cron Calendar.
Meeting Scheduler for Gmail - Easy scheduling directly from Gmail