WUBS (Web User Booking System) has been developed at Loughborough University Library to allow online booking of resources (rooms, PCs, etc) directly by end users. It has been in production use at Loughborough since October 2004.
Allows resources to be of arbitrary, admin defined types. For example you might have types of "Group Study Room", "Bookable PC", "Staff Loan Laptop", with multiple resources of each type
Individual resources can have different booking periods defined, with gaps allowed between booking slots (allowing, for example, one group to a room and then another group takes up residence outside of the booked slot)
Resources and/or types can have periods defined when they aren't available for bookings (eg during holidays or building refurbishments)
"Librarian" and admin staff can act as other users to allow them to book resources on behalf of students (handy if sitting at a help desk or on the end of a support line)
Different classes of user can have different limits to the number of resources they can book, with different rules for different types of resource as well
User information picked out of the Active Directory