I'm sure you all know that it's possible to create plugins and extend various aspects of the jQuery JavaScript library but did you know you could also extend the capabilities of it's selector engine?
In it's simplest form, you can create a MultiSelect form control using the following code:
$(document).ready( function() {
$("#control_id").multiSelect();
}
where #control_id is the ID of the select element that exists on your page. You can use any valid jQuery selector as the ID, but make sure you only use select elements with the multiple="multiple" attribute to get the expected results.