Have Fun With RIAnimation (Free Library)
RIAnimation is a small and handy library, written with jQuery and full integrated with ASP.NET.
With RIAnimation you can take pretty UI effects to controls in web pages.
RIAnimation is easy to use and you may see all of it's usages here and download it from here.
Meanwhile it is full free.
you can use it in Design time or Programmatically in code behind.
Design time :
<hhm:RIAnimator ID="RIAnimator1" runat="server" TriggerControlID="BtnDemo" TargetControlID="PnlDemo" TriggerEvent="Click" Animation="Bounce"></hhm:RIAnimator>
Programmatically (if you want to take "SlideInFromTop" effect on "pnlDemo" panel, when mouse is down on panel ) :
HHM.RIAnimation.RIAnimator RIA = new HHM.RIAnimation.RIAnimator();
RIA.TriggerControlID = PnlDemo.ID;
RIA.TriggerEvent = HHM.RIAnimation.Options.TriggerEvent.MouseDown;
RIA.Animation = HHM.RIAnimation.Options.Animation.SlideInFromTop;
this.Page.Controls.Add(RIA);