Yes, the mouse is a great tool, but a few good shortcuts are a little more handy.
The ALT+SPACEBAR combination will yield a few of those handy, yet hardly ever remembered, shortcuts:

ALT+SPACEBAR+C, will Close your application window.  This is very comfortable to use because of the proximity of the three key strokes.  ALT+F4 will produce the same results, but the keys are very far apart.

ALT+SPACEBAR+N, will Minimize your application window to the Task bar.  You'll never track down that little (-) sign again!

ALT+SPACEBAR+X, will maXimize your application window to fit the screen resolution.  Another very easy combination to perform.