dhtmlxScheduler – Ajax Events Calendar/Scheduler

dhtmlxScheduler is a Web-based JavaScript events calendar that provides rich and intuitive scheduling solution similar to Microsoft Outlook Calendar, Apple’s iCal or Google Calendar. Due to dynamic data loading via Ajax the calendar events can be added/modified/deleted without refreshing the page. Advanced drag-n-drop functionality allows users to change events dates and time by easily moving or resizing event boxes. The events can be displayed in Day, Week or Month views. At the same time, the scheduler is very lightweight (about 19Kb gzipped) and fast-performing.
(Link: dhtmlxScheduler – Ajax Events Calendar/Scheduler)