HEY - Email at its best, new from Basecamp.
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.
InstAddr - Disposable email address application.
Acuity Scheduling - Automate your client bookings, cancellations, reminders & payments using the worlds friendliest online scheduling software.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
Doodle - Make meetings happen. With Doodle, scheduling becomes quick and easy.