WebCalendar is a PHP-based calendar application that can be configured as a single-user calendar, a multi-user calendar for groups of users, or as an event calendar viewable by visitors. Version : 1.2.7
ExtCalendar is an open-source calendar application, with an integrated event managemt system.
ExtCalendar is a powerful multi-user web-based calendar application. Features include Multi-Languages, Themes, Recurrent Events, Categories, Users and Groups management, Environment and General Settings, Template Configuration, Product Updates. Version : 2.0
phpScheduleIt is an Open Source web-based reservation and scheduling system, allowing users to register and then place reservations on any kind of resources, such as conference rooms, machines, computers, etc. The administrative side allows complete control over user permissions, resource data, reservation data, and is has many configurable settings. Version : 2.4.2