this depends on what game youre playing. For example, playing WoW in windowed mode is perfect. Set it to windowed and maximized, you dont see the window borders, and you can mouse off easily for other monitor apps.
you obviously dont want to do that with games like FPS's and such, but i havent found a way to not make it minimize.
edit: BTW nice post count. 10000 on the dot. congrats, lifer.