Appointment Booking Calendar - With the Appointment Booking Calendar you can accept online bookings from a set of available time-slots in the calendar.

Booked Scheduler - Booked (formerly phpScheduleIt) is a simple but powerful reserve-anything scheduler.

MakePlans - Online appointment booking - MakePlans

Celcat Timetabler - Celcat Timetabler is the complete, state of the art solution for optimising resource utilisation, timetable publication, ad-hoc room booking, attendance tracking, pay claim management...

Dudle - Dudle is an online scheduling application, which is free and open source.

QReserve - QReserve is a powerful resource booking, lending, showcasing, and reporting platform.