You'd be wise to arm yourself with an International Student Identity Card (ISIC), which offers substantial savings on rail passes, plane tickets, and entrance fees. It also provides you with basic health and life insurance and a 24-hour help line. The card is available for $22 from STA Travel (tel. 800/781-4040; www.sta.com), the biggest student travel agency in the world. If you're no longer a student but are still under 26, you can get a International Youth Travel Card (IYTC) for the same price from the same people, which entitles you to some discounts (but not on museum admissions). (Note: In 2002, STA Travel bought competitor Council Travel after it went bankrupt. It's still operating some offices under the Council name, but it's owned by STA.)
Travel CUTS (tel. 800/667-2887 or 416/614-2887; www.travelcuts.com) offers similar services for both Canadians and U.S. residents. Irish students should turn to USIT (tel. 01/602-1600; www.usitnow.ie).