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.
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').
DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.
Ultramon - UltraMon is a piece of software built to help with the management of multiple screens on the same computer system. Without software like this, taking full advantage of an expanded desktop space can be difficult.
9Desks - up to nine virtual desktops