Animated rollover menus

I want to create a menu like on the site

Where the options expand when you roll the mouse over and contract when you move the mouse away, and the options underneath move up and down in tandem. I assume it needs ActionScript which I don’t have much knowledge of.

Could anyone point me to a tutorial that deals with this please? I can’t seem to find one, but I’ve seen the effect fairly regularly so someone must know how to do it!