VirtuaWin - VirtuaWin is a virtual desktop manager for the Windows operating system (Win9x/ME/NT/Win2K/XP/Win2003/Vista/Win7/Win10). A virtual desktop manager lets you organize applications over several virtual desktops (also called 'workspaces').
Dexpot - If you don't have Dexpot yet, the new update makes it a must-have tool for Windows, adding a ton of features to your desktop that you never knew you wanted.
9Desks - up to nine virtual desktops
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.
WindowsPager - WindowsPager is a desktop-switcher/pager for Windows to manage virtual workspaces/desktops.
nView - Effectively manage your desktop with NVIDIA nView.