Contexts - Switch between application windows effortlessly — with Fast Search, a better Command-Tab, a Sidebar or even a quick gesture. Free trial available.
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').
VistaSwitcher - VistaSwitcher is an elegant and powerful task management utility for Windows OS.
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.
Witch - Welcome to the world of W. i. t. c. h.
9Desks - up to nine virtual desktops