[support] expandable menu

Hi, I need to make a horisontal main menu that is expandable on click. Kinda like the one they use on flickr for example - you know: a list of menu items with a little arrow, and when you click it, the item reveals the sublinks. Sounds very simple, but I've been trying for a few days now to incorporate all kinds of scripts into drupal, but without luck. Could some kind soul pleeeease help me with a few pointers? thanks for listening! cheers Morten