i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
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').
dwm - dwm is a dynamic window manager for X. It manages windows in tiled, monocle and floating layouts. All of the layouts can be applied dynamically, optimising the environment for the application in use and the task performed.
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.
Xmonad - xmonad is a dynamically tiling X11 window manager that is written and configured in Haskell.
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.