Dutch Flyer
Formerly known as the Amsterdam Express, Stena Line's Dutchflyer service provides city-to-city travel for anyone wishing to travel from Britain to Holland by train and ferry.
http://www.dutchflyer.co.uk/
http://www.stenaline.co.uk/

NS - Netherlands Railways
The homepage of the Dutch national rail operator.
http://www.ns.nl/

Rick Steves'
A detailed guide to European rail passes.
http://www.ricksteves.com/rail/home.htm