Amsterdam Tourist Board
Everything you ever wanted to know about Amsterdam courtesy of an official source.
http://www.visitamsterdam.nl/

City of Amsterdam
Official homepage of the city of Amsterdam, with information about the local government, business, health, education, housing, tourism and lots more.
http://www.amsterdam.nl/

Holland
Website of the Netherlands Board of Tourism and the Netherlands Foreign Trade Agency. Contains a useful guide to Amsterdam.
http://www.holland.com/
http://www.holland.com/amsterdam/gb/

Tourism North Holland
Tourist information for the North Holland region, of which Amsterdam is the focal point.
http://www.noord-holland.com/