Vimcal - Vimcal is the world’s fastest calendar, beautifully designed for people who work remotely and live in their calendars.
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.
Plan - Plan is a better way to organize.
SavvyCal - A scheduling tool both the sender and the recipient will love.
Clean Google Calendar - Makes Google Calendar look nicer & launches as a desktop app
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.