HoverIntent. You Need It.

I've been using a commercial product at work that has a jumpy and annoying menu system in it.  Every time I use it, I only think one thing:

"They need some HoverIntent"

HoverIntent is a jQuery plugin that extends the "hover" event into something much, much better.  It's become a really standard tool for my pages and any page I encounter that isn't using it and uses a hierarchical menu (such as the product initially mentioned), it drives me kind of nuts.