Depending on what window manager you are using, there is normally a way to exit x; usually via some menu item or whathaveyou. If you are running gnome (which I seriously doubt) then you just access the main menu then choose logout (AFAIR) should be something similar for KDE.

Window managers such as blackbox usually allow you to define your own menus completely so having that sort of option would depend on you having put it/left it in your menu config. But basically, I would check the site for your window manager.

I know this isn't what you want, but if you ever need to bring the console up while you are running x or require more consoles, you can press [ctrl]-[shift]-[f#] (f# being one of the f keys [i.e. F1, F2, etc]) and a new console will come up.

ac