ZZEE DHTML Menu is an easy to install library for Javascript and PHP that you can use to create familiar dropdown menus like in desktop applications. It comes with many options, including checkboxes, radios, keyboard navigation, shortcuts, ability to add or delete items on the fly, etc. Simple API. Search engine friendly (PHP ver. only). ZZEE DHTML Menu ships with four different styles. The program is free for non-commercial use. Unlimited websites allowed.