The program arbtt, the automatic rule-based time tracker, allows you to investigate how you spend your time, without having to manually specify what you are doing. arbtt records which windows are open and active, and provides you with a powerful rule-based language to afterwards categorize your work.
i3 is a dynamic tiling window manager. Its key features are correct implementation of Xinerama (workspaces are assigned to virtual screens, and it does the right thing when attaching new monitors) and XrandR support (which is still unfinished). Both horizontal and vertical columns can be used in tiling. There is a special focus is on writing clean, readable, and well documented code. i3 uses xcb for asynchronous communication with X11, and has several measures to be very fast. i3 is primarily targeted at advanced users and developers.