Appointment Booking Calendar - With the Appointment Booking Calendar you can accept online bookings from a set of available time-slots in the calendar.
Timestead - Job Sheet and Jog management software as a service.
Dudle - Dudle is an online scheduling application, which is free and open source.
AroFlo - Job management for trade services & project based industries
MakePlans - Online appointment booking - MakePlans
Fieldax - Field Service Management - Best Field Service Software for Small and Medium Field Service Businesses