Depending on where you go, youth and student cards can be good for discounts on lodging, travel and entertainment. Some agencies also sponsor study/work abroad programs. Before you buy a card, keep in mind that in the EU you have to be an EU citizen to get these discounts at museums and in Southeast Asia everything's so cheap it don't matter.

Student Travel Association 800-777-0112. I love STA cuz although I'm not a student they saved us a lot on airfare.

International Student Identity Cards

Council on International Educational Exchange  800-266-8624
205 East 42nd St. New York, NY 10017
212-822-2600 or info@ciee.org