Window managers are programs that allow a user to interface with their computer. I currently use the EXWM window manager, but I've used Bspwm, i3 and herbstluftwm in the past. On MacOS and Windows, this is your standard user interface, just as it is with Gnome or another desktop management service in Linux.
wmutils: tools for X window manipulation. These can be used to script your own window manager!
autorandr automatically detects the current display and loads the appropriate X window setup.
https://github.com/baskerville/xtitle gets x window titles
https://github.com/salman-abedin/devour script to open a tool created by a terminal on top of the terminal rather than allowing the terminal to waste space
Cool WM projects
bug.n is a tiling window manager for Windows written in AutoHotkey.
https://github.com/conformal/spectrwm fun tiling wm