Thr Institute of Patent and Trade Mark Attorneys Australia (IPTA) http://www.ipta.com.au/

IP Australia (Patent, Trade Marks and Designs Office)
http://www.ipaustralia.gov.au

United States Patent and Trademarks Office (USPTO)
http://www.uspto.gov

European Patent Office (EPO)
http://www.european-patent-office.org

Japanese Patent Office (JPO)
http://www.jpo.go.jp

World Intellectual Property Organisation (WIPO)
http://www.wipo.org

For other interesting and useful links, see the "Links" page of the IPTA website:
http://www.ipta.org.au/IPTAlinks.html