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.
Gameclock is a fairly simple application designed to track the time spent thinking by the players during a chess game. Various clock engines are available (speed chess, fisher chess, board games, or hourglass). The graphical interface is keyboard-driven and is intended to be minimal and simple. The code is made to be extensible to other game types.