You are probably familiar with the ripple effect when opening a Dashboard widget. But there are two animations that you may have not yet seen.

If you usually double click the widget icons in the tray to open them, you may want to try to drag them out rather. The benefit of this action is that you can instantly position them while they are launching. The animation for this operation is a morph between the icon and the full size widget followed by a ripple.

The other trick - if your widget is misbehaving or just not updating you can hit Apple-R (Cmd-R). The widget will instantly relaunch with a cool twirl animation.