I happened to be on the international train yesterday and as I walked into the train car I noticed all the colors were different in second class, and there was a promotional web address written on the windows NSHispeed.nl

After some research I've learned that the high speed rail lines from Amsterdam to Rotterdam and beyond (to Brussels, Paris, Cologne, etc) are almost complete. This means, that as of December of this year, you can take a wonderfully fast Thalys, Eurostar, or ICE train and travel at speeds just under 120MPH (200KPH). Beyond that, apparently for national rail travel between Amsterdam-The Hague-Rotterdam-Breda they're introducing a new kind of TGV train. EXCITING!

Of course the full high speed power won't be ready til 2010, at which time you can get to Paris in 3 hours, Brussels in 1 hour 46min, or Frankfurt in just under 4 hours. Naturally it won't be the cheapest thing in the world, but with the amount of trains available to choose from, it will certainly be affordable in comparison to the cost and stress of dealing with air travel to cities that are all nearby.

By the way, if you go to the website click on the part "Our Network" there's a great little animation that shows you an animated comparison of flying, driving, and taking different kinds of trains... it's cute!