The Najonalbibliteket in Oslo, Norway, is a goldmine of records for genealogists. The library is located in a large older building in Henrik Ibsens gate 110 in Oslo. There you will find a multimedia center of information concerning Norway, Norwegians and Norwegian culture. The collection includes of manuscripts, special collections of books, music, radio and television programs, film, theatre, maps, posters, pictures, photographs and newspapers.
The Nasjonalbiblioteket is the largest library in Norway and its function is similar to that of The Library of Congress. By law they are to receive a copy of everything that is published in all media formats in Norway, and as such it is a great repository for most Norwegian records. You may search their catalog online. For more information see the Nasjonalbibioteket article in Wikipedia.