You have a library or internet-cafe?You want to organize the surf-time?This ticketing and domainserver is the best way to do that. Create a user, select the time he can surf and a ticket is printed out with the information(and/or price) to log in on a random pc workspace.The user can log in and surf as long as the ticket value. About 5 minutes before the surf-time ends the users gets a warning on the screen that his time is almost up. Nice and easy.