Dormitory Delights

There doesn't seem to be any central source of information about them, but rooms in college or university dormitories are still a good bet during school vacations. Many Canadian unviersities open their residences to non-students during the summer, as do some in the United States, in Spain, Scotland, Ireland, Malta and Argentina, among others I have written before about the many options available in student residences in high-priced London during school holidays. Near New York City, Long Island University offers rooms to visitors starting at about $50 a night when classes are not being held.
Usually rooms in residences are considerably cheaper than those in commercial lodging (other than hostels,) and they often come with other perks like low-cost dining options and use of sports facilities. Generally the rooms are singles, with shared bath.
B & J Publications used to put out a book called "Campus Lodging Guide" with details on residences open to visitors, but unfortunately the last publication date seems to have been 1999. If there are Websites offering similar information on a number of such residences in different universities, cities and countries I have not been able to find them. Such a listing, preferably with an online reservation form, would be very helpful to budget travellers.
So, for the moment you have to do some research yourself. If you plan to visit an expensive city during summer or over Christmas, check out its colleges and universities to see if you can book a room and save some bucks. And if all else fails, you can always sign up for a summer course that gives you access to on-campus housing.