Stupid Mouse Trick
Short and sweet. Just discovered this trick. In KDE (currently using 3.5.4 FC5) if you move your mouse over the kpanel with more than one application running and over the apps or desktop area... you can use the scrolly mouse wheel to cycle through your apps. from all your desktops. An alternate keyboard method is with Alt+Tab/Ctrl+Tab but those will only alternate between apps. in the current desktop.