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.
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.
awesome - A dynamic window manager for the X Window System developed in the C and Lua programming languages.
9Desks - up to nine virtual desktops