At work I have a UNIX workstation with 2 monitors.
21 inch monitor that has 6 virtual desktops that I use for netscape, calendar, email, process manager, etc.
And 24 inch monitor with 10 virtual desktops that I do work on schematics, simulations, etc.
I usually add a virtual desktop for each new assignment I am working on. That way when I want to switch to some task, I have all the things set up in it's own desktop. I usually work on ten different things at once.