TimeBreak is a simple utility that, when installed on your computer, can monitor your kids' time spent on the computer, and automatically log them off or lock their session when their assigned time is up. You can configure how much time is available for each kid each day of the week, and also specify allowed time ranges (e.g. no computer use before 6:00 pm). Additionally, you can specify bonus rules, letting your kids earn points for fulfilling various tasks (like chores), in order to be awarded with bonus time.
TimeBreak can be installed on one or multiple computers. If installed on multiple computers with a network connection, TimeBreak can synchronize settings and time usage information between all the computers (e.g., if a kid spends all his allowed time on one computer, he will not be allowed to log into any of the other computers for the rest of the day).