Using the graphical desktop environment without the mouse might seem counter-productive, but try the keynav tool, and you'll see that the idea makes sense -- at least in certain situations. For example, when you don't have enough space to use the mouse, or the trackpad on your netbook or notebook is not really great, keynav can come in rather handy.

The way keynav works is pretty clever. When activated using the Ctrl+; keyboard shortcut, keynav splits the screen into four parts, and you use the keyboard keys to "zoom" on a specific area of the screen and then move the cursor to the center of the area. keynav supports the following keyboard shortcuts:

h selects the left half of the region
j selects the bottom half of the region
k selects the top half of the region
l selects the right half of the region
shift+h moves the region to the left
shift+j moves the region down
shift+k moves the region up
shift+l moves the region to the right
semicolon moves the mouse to the center of the selected region
spacebar moves the mouse and left-click
escape cancels the move

Getting to grips with keynav can take some time, but once you've mastered the basics, you can command your desktop without using the mouse.