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.
Mixmax Calendar - The fastest way to schedule meetings with anyone, anywhere
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Meetingbird for Gmail - View your calendar and schedule meetings right from Gmail
SavvyCal - A scheduling tool both the sender and the recipient will love.
FreeBusy - Easiest way to share availability across calendars for free