This example demonstrates a AjaxTimerBehavior as well as updating of multiple components on the page.
This AjaxTimerBehavior can be attached to any component and will recieve a callback every x number of milliseconds. Within this callback it is very simple to update any number of components via ajax.

Los Angeles: | [la clock]
New York: | [ny clock]
London: | [london clock]
Prague: | [prague clock]
Moscow: | [moscow clock]