The Procrastinator's Timeclock is a simple utility for people who suffer from excessive procrastination or distractibility. The utility achieves its benefits by allowing you to comfortably track just how much time your little "one more thing"s are adding up to and by helping to bolster willpower by providing a gentle distraction from temptations. Its design focuses on simplicity, intuitiveness, and a preference for keeping existing users rather than attracting new ones.
QuickTile is a simple attempt to duplicate the basic functionality of WinSplit Revolution for users who don't like the Compiz Grid plugin. It should work on any X11 desktop with PyGTK 2.2+, a window manager that supports the modern range of NETWM hints, and (if you want internal keybinding) python-xlib.
timekpr will track and control the computer usage of your user accounts. You can limit their daily usage based on a timed access duration and configure periods of day when they can or cannot log in. With this application, administrators can limit account login time duration or account access hours. It has support for GNOME, KDE, and XFCE and uses time and access Linux PAM modules. It is currently limited to Ubuntu only.