i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
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.
Toggl - Toggl is an online time tracking tool. It features 1-click time tracking and helps you see where your time goes. Free and paid versions are available.
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.
Pomodone - Pomodone is the easiest way to track your workflow using Pomodoro technique, on top of your current task management service.