It is common to hear that recent advances in the Linux desktop, such as Compiz Fusion, are more of a fancy but useless aesthetic contribution to the desktop. While it may be true for many of the CF features, it is no less true that you never know when a given effect will turn out to be useful.
In this post I want to praise the Enhanced Zoom Desktop plugin. It turned out to be of great use for me in the following situation. I wanted to run Diablo II in my laptop (yes, it runs in Linux, under Wine). The native resolution of the program (640x480 or 800x600) is lower than that of my screen (1280x800), so I have two options: to execute it in windowed mode, or fullscreen. In windowed mode the window occupies less than 2/3 of the 13.3" screen, wasting space and making it unnecessarily small. Fullscreen mode seems to be better, but it isn't. Since the width/height ratio is smaller for Diablo than for the screen, the former will be stretched horizontally, distorting the images (everything looks more squat). Fullscreen mode also gave me other problems, like crashing more easily when alt-tabbing.
Here is where the zooming of Compiz Fusion comes in handy. Apart from an arbitrary zoom (using the mouse wheel while pressing the Super key, a.k.a. windows key), there is a handy shortcut (Super+r) that zooms up to the point of the screen under the cursor occupying the whole screen. When zooming, the movement of the mouse makes the zooming "window" to move around, showing different parts of the desktop. To avoid it (clearly unwanted if we want to stay inside the Diablo window), we have another shortcut: Super+l. This shortcut toggles on and off the "zooming lens follows the mouse" movement.
So now, if I want to play Diablo I open it in windowed mode, then put the cursor inside the window, then hit Super+r, then Super+l, and I have a Diablo window as big as possible to fit in my screen, preserving height/width ratio, and keeping the mouse inside the window.