Libraries, reports, articles and other relevant links:

Australia
Office of film and literature classification: http://www.oflc.gov.au/
Search the OFLC database: http://www.classification.gov.au/special.html?n=44&p=155
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/australia.html
National Library of Australia: http://www.nla.gov.au/
Electronic Frontiers Australia Inc. On Censorship and free Speech: http://www.efa.org.au/Issues/Censor/

Canada
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/canada.htm
National Library of Canada: http://www.nlc-bnc.ca/
A Chronicle of Freedom of Expression in Canada: http://www.efc.ca/pages/chronicle/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/canada.html

Denmark
FAIFE: http://www.ifla.org/faife/
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/denmark.htm
The Royal Library: http://www.kb.dk/index-en.htm
Prints of illegal newspapers during WWII (in Danish): http://www.kb.dk/kultur/expo/illegale/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/denmark.html

France
National Library of France: http://www.bnf.fr/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/france.html

Germany
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/germany.htm
National Library of Germany: http://www.ddb.de/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/germany.html

Iran
National Library of Iran: http://http://www.nlai.ir/Default.aspx?tabid=401/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/iran.html

Italy
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/italy.htm
National Library of Italy: http://opac.sbn.it/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/italy.html

Japan
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/japan.htm
National Diet Library: http://www.ndl.go.jp/en/index.html
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/japan.html

Lithuania
Censorship in Lithuania 1940-41 - article
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/lithuania.htm
National Library of Lithuania: http://www.lnb.lt/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/lithuania.html

Malawi
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/malawi.html

Norway
Freedom of expression in Norway - article
National Library of Norway: http://www.nb.no/english
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/norway.html

Peru
The Lima Inquisition and Book Censorship, 1570-1820 - article by Pedro Guibovich
National Library of Peru: http://www.bnp.gob.pe/portalbnp/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/peru.html

Poland
National Library of Poland: http://www.bn.org.pl/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/poland.html

Russian Federation and the Soviet Union
Censorship in Russia in 19th and 20th century - article
National Library of Russia: http://www.nlr.ru:8101/eng/
Russian State Library: http://old.rsl.ru/eng/defengl.asp
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/russia.html

South Africa
Censorship in South Africa during the apartheid regime - article
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/south_africa.htm
National Library of South Africa: http://www.nlsa.ac.za/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/southafrica.html

Spain
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/spain.htm
National Library of Spain: http://www.bne.es/index_eng.htm
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/spain.html

Turkey
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/turkey.htm
National Library of Turkey: http://www2.mkutup.gov.tr/index-eng.html
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/turkey.html

United Kingdom
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/uk.htm
British Library: http://www.bl.uk/
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/uk.html

United States
IFLA/FAIFE World Report: Libraries and Intellectual Freedom: http://www.ifla.org/faife/report/united_states.htm
American Library Association: http://www.ala.org/cipa/
Challenged and banned books: http://www.ala.org/bbooks/challeng.html#mfcb
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/us.html
Library of Congress: http://www.loc.gov
Banned Books Online: http://digital.library.upenn.edu/books/banned-books.html

Vatican City State
The Index Librorum Prohibitorum - article
Guide to Law Online (Library of Congress): http://www.loc.gov/law/guide/holysee.html
Vatican Library: http://www.vatican.va/library_archives/index.htm
Index Librorum Prohibitorum, of 1949: http://www.cvm.qc.ca/gconti/905/BABEL/Index%20Librorum%20Prohibitorum-1948.htm