fruux - Free service that takes care of your contacts, calendars and more so you don't have to.
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.
FullContact - Put the power of full contact information into your web or mobile apps.
Acuity Scheduling - Automate your client bookings, cancellations, reminders & payments using the worlds friendliest online scheduling software.
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Doodle - Make meetings happen. With Doodle, scheduling becomes quick and easy.