Here's a twist on multiple desktops: software from Cubedesktop increases your working space by offering you a 3D virtual desktop environment. With Cubedesktop, you will have 6 virtual desktops which you can move between in different ways, one of which is a 3D cube. As you move from desktop to desktop, you will see a live preview of what's happening. All the windows update in real time, so you can find just the one you are looking for. Each desktop can be named (like "work," "school," or "fun") and can have its own wallpapers and icon arrangement.
Besides the 3D cube, you can also use features like the "Window Exposer," which tiles the open windows on to your screen, or a simpler Desktop Explorer. The software is available as a free trial for both XP and Vista (does not specify if x64 supported). (via Go2web20)