ProtoFish is an advanced hover menu based on Prototype, written by Peter Slagter. You can easily add a delay to your menu (on mouseout) and choose your own hover class. All ProtoFish menu's will respond to users who use the TAB-key to navigate through your page. It’s free and you're allowed to use ProtoFish without any constraints. Rip the code apart or add some features - use it the way you like!
More info: ProtoFish