COWS == Cluttered Open Window Syndrome, referring to having tons of windows open on your screen at the same time. For some people this is a problem, for other it's heaven.
One of my favourite features of Radio 8 on Mac OS X (and 9 for that matter) is it doesn't have an MDI prison. Multiple monitors attached, and I can work on all of them. Ahhh.... smell the wide open desktop!
Mozilla, mind you, is the ultimate freedom. Tabbed browsing, and multiple windows. It's so effective.