MagicAjax.NET The classic AJAX engine for ASP.NET developers.

using MagicAjax;
using System.Web.UI;

public partial class Default : Page
{
  protected void btnRefresh_Click(object sender, EventArgs e)
  {
    // no postback. no flicker. just magic.
    AjaxCallHelper.Write("document.title",
      "Updated @ " + DateTime.Now);
    panel.Update();
  }
}