awesome - A dynamic window manager for the X Window System developed in the C and Lua programming languages.
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.
i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
MoneyPenny - Track time and expenses, issue professional invoices and manage projects in one place. MoneyPenny is the best solution for your business.
Abby Connect - Abby Connect is the top-rated, US-based virtual receptionist team with elite training, custom call handling, free extended hours, and a 14-day free trial.
i3-gaps - i3-gaps is a fork of i3wm, a tiling window manager for X11.