Well, DHTML Menu Studio creates drop down site navigation menus. When you roll-over the the "root", the sub-menu items fly out. There's a demo here:
http://www.xtreeme.com/dhtml/
Unfortunately mine is on an intranet, so can't really show you. Anyway, here's a screenshot of my menu (slightly expanded):
Note my cursor on top of the left navigation, but nothing comes out.
Here's a 2nd screenshot of it actually working: