ASPxScheduler Suite

From Developer Express:

Built and optimized for ASP.NET 2, the ASPxScheduler Suite includes all the elements you will need to create stunning web applications that mimic the capabilities found in Microsoft Outlook's scheduler. This suite ships with a complete set of timeline presentation formats, including those unavailable with other scheduling component libraries - the horizontal timeline view and side-by-side calendar display

Additionally, the ASPxScheduler Suite delivers a myriad of features including event recurrence support, drag-and-drop as all as appointment resizing support, advanced date navigator, built-in editor dialogs and helper buttons allowing you to easily navigate between scheduled appointments

All the features mentioned above have been built on top of our core ASP.NET library, thus providing lightweight rendering and high responsiveness via AJAX callbacks