ANSWER:

I recently released SelectBoxIt three weeks ago, and it is already pretty stable (the current version is 0.6.0). It is jam packed with features so check it out.

SelectBoxIt Notable Features:

• Styleable with the jQueryUI Themeroller (optional)

• Supports all jQuery and jQueryUI show/hide effects (optional)

• Supports all jQueryUI/custom icons

• Includes ARIA (Accessible Rich Internet Applications) support

• Full keyboard search and navigation support

• An event API triggered on the original select box element that calls the plugin

• A method API providing methods to interact with the dropdown list (i.e. Search, Open, Disable, Set Options).

• Passes jsHint with no errors

• Selected, Disabled, and Optgroup Support

• Easily extendable to allow developers to create new widgets

by Greg Franko from http://stackoverflow.com/questions/10439534