Multiple select is a jQuery plugin to select multiple elements with checkboxes. Multiple Select supports methods that allow programmatic control of the component.
Multiselectable jQuery Plugin makes easy to choose multiple items from list with 2 select lists. One with the available options and one for the options that we need to select. It’s been used before but if you are jQuery fan then this is nice (and clean) implementation of the technique.
TabSelect is a plugin to select one or more array or form entries visually, for example to filter a list or replace a multiselect form element.
Chosen is a JavaScript plugin that makes long, unwieldy select boxes much more user-friendly. It is currently available in both jQuery and Prototype flavors.