Windows usually spawn at the leftmost corner. Having a "center to the middle of the window"-key would make it easier to work with the keyboard only.

Using the Gnome environment mainly with keyboard has gotten easier with such programs as Deskbar Applet and Gnome-Do. Gnome windows usually spawn at the leftmost corner of the window. The only way to move the window to the center of the screen is to drag it with the mouse. Having a shortcut key for centering the window would enhance the keyboard-only usage of the Gnome environment.