Throbbo is a jQuery plugin that makes is easy to display a throbber (aka spinner) while loading.
Show throbber as an overlay in #foo. Throbber will show for 2 sec.
$('#foo').throbbo({duration: 2000});
Show throbber as an inline image inserted before #bar.
$('#bar').throbbo({duration: 2000, mode:'insertBefore'});