A freely available desktop manager exists from none other than the MotherShip herself. It lacks the fullness of features that can be found in the imaginatively named:
for OS X (and supporting Tiger, and as an added bonus, working quite well on an Intel-based Powerbook, though I didn't check its status in the aforementioned Rosettatest) - this cool app has a half-dozen or so available transitions between pages, flexible ways to change screens, and many other cool features. Now if only I coluld assign a new desktop to each "virtual" desktop.
Manage up to four desktops from the Windows taskbar with this PowerToy. - Microsoft's description is as good as any. Unfortunately, this is all it does, and it offers no thumbnails of screens, and no nifty transitions. It works on XP, not 2k or 9x.
MS's description: With this PowerToy, in addition to seeing the icon of the application window you are switching to, you will also see a preview of the page. This helps particularly when multiple sessions of an application are open.I say: This has been around a while, and I wish MS would do more along the lines of these two power toys to innovate on the interface. This reminds me a bit of how OS X and other desktop managers use thumbnails to show you whats up - I use a hot corner in OS X to activate Expose's "All Windows" function - quickly filling my screen with clickable perfect little thumbs of my work.