FullCalendar - FullCalendar is an open-source JavaScript event calendar.
Qloapps - Open Source System - Build Hotel Booking Website and Manage Online & On-Desk Bookings.
Doodle - Make meetings happen. With Doodle, scheduling becomes quick and easy.
FewohBee - Web based management tool for hotels, pensions, accommodations and vacation homes
Dudle - Dudle is an online scheduling application, which is free and open source.
BSI Hotel Booking System - BSI Hotel Booking System is a real time online hotel booking.