MakePlans - Online appointment booking - MakePlans
Launch27 - Online booking & appointment scheduling.
Appointment Booking Calendar - With the Appointment Booking Calendar you can accept online bookings from a set of available time-slots in the calendar.
The Customer Factor - Field Service Management
Dudle - Dudle is an online scheduling application, which is free and open source.
CleanTelligent - CleanTelligent is business management software built from the ground up for use by janitorial service companies.