I arrived today at Amsterdam Airport and followed Rick's advice about buying train tickets -- in my case into Amsterdam's Centraal Station. Rick recommends using the "Train Tickets and Services" counter in Schiphzl Plaza on the ground floor just past the Burger King. Rick says this agency accepts US credit cards. UNFORTUNATELY NO MORE. Beware: They now only accept credit cards with pins. Also, they raised their fee from 0.50 Euro per ticket to 1.00 Euro per ticket. For the cheap 4.10 Euro ticket from the airport into Amsterdam's Centraal Station, this represents a 25% fee -- a rip off in my book. I have no good alternative suggestions. I guess if you have coins, you could use a ticket kiosk.
As an editorial comment, I have been in Europe now for 10 days and have noticed that a majority of the places that deal with tourists have compensated for the high dollar, by raising their prices in Euros. This is at palaces, museums, and now ticket agencies. I think this is a form of greed, and they do it because they can.