Pulse 24/7 - Booking & scheduling mobile app for service providers
Dudle - Dudle is an online scheduling application, which is free and open source.
MakePlans - Online appointment booking - MakePlans
Appointment Booking Calendar - With the Appointment Booking Calendar you can accept online bookings from a set of available time-slots in the calendar.
Set a Time - Appointment scheduling software for businesses to accept appointments online from customers and clients.
Acuity Scheduling - Automate your client bookings, cancellations, reminders & payments using the worlds friendliest online scheduling software.