DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
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').
Actual Multiple Monitors - Actual Multiple Monitors is a software utility which offers the comprehensive solution to improve the functionality of Windows user interface for comfortable and effective work with multi-monitor configurations.
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.
Synergy - Project management & accounting for AEC professionals
9Desks - up to nine virtual desktops