Try the online demo: AJAX-style event creating, moving, resizing, and deleting • Context menu • Day view • Work week view • Week view • Month view • Horizontal/vertical resources view • PostBack/AJAX/JavaScript event handling • Binding to XmlDataSource, SqlDataSource, DataTable, ArrayList • Custom event formatting • UpdatePanel compatibility

protected void DayPilotCalendar1_BeforeHeaderRender(object sender, BeforeHeaderRenderEventArgs e)
{
  e.InnerHTML = "<img src='yourimage.png' width='15' height='15' /> " + e.InnerHTML;
}

DayPilot Pro is an advanced DayPilot edition. You can check a thumbnail overview of the most interesting features. There is also an online demo with all the features working (including the AJAX features). If you want to test the design-time support and API you can download a fully functional trial version. And if you like it, you can buy a full version with source code and 12 months of upgrades and support (with a 30-days money back guarantee).

DayPilot Lite is a do-it-yourself open-source edition of DayPilot. Although it misses some DayPilot Pro features, there are thousands of developers using it to build calendar, personal scheduling, and resource booking applications.