DHTMLX
  
DHTML eXtensions - professional AJAX components for advanced Web UI.

Features details

Initialization from HTML Select/XML/Javascript

You can convert existing select boxes to dhtmlxCombo objects automatically enabling automatic conversion, or manually with a script method. The combobox can also be initialized from xml or javascript.

Filtering

Filtering means the ability to narrow the already loaded list by typing in the combobox. You can try it in the Live Demo on component home page.

Autocomplete

It is easy to implement autocomplete functionlity with dhtmlxCombo. In contrast to filtering, autocomplete loads values from the external datasource, while the user types in the Combobox. A live sample, which works with thousands of possible values, is available.

Ability to include images or other objects in list

dhtmlxCombo has native support for including images and other objects (like checkboxes, for example) into the list