Prefer - Professionals you need, from people you know
Appointment Booking Calendar - With the Appointment Booking Calendar you can accept online bookings from a set of available time-slots in the calendar.
Warmspace - Tech-powered conversations that transform relationships in work and life.
MakePlans - Online appointment booking - MakePlans
Introwise - All-in-one scheduling and business management platform for coaches, tutors and consultants to run their business online.
Dudle - Dudle is an online scheduling application, which is free and open source.