This site uses an old variant of Ross Cairns's Expanding Menus. I can't remember where I've got it but you can download the js file here

I have added a cursor: pointer; property to #menu ul li.section-title so that the cursor changes shape on the section titles

Indexhibit forum thread

Expanding Menus gave an error on expandingMenu (0) and following ordinals, and it broke cycling on all slideshows. I commented out each of the expandingMenu(#) and the error disappeared, slideshows work again and the expanding menus still work alright. May be the new JQuery, apparently it's just enough to have the expandingMenus.js call in the index.php