Uhh... also changing money at a bank in the US gives you a REALLY terrible international rate - plus you usually can't just walk in and do it (eg they have to order the currency)

The cheapest (?best) way is to just get cash out of an ATM as soon as you get into the country - many airports have them right there. As for exchanging money back that's harder because you lose the "commission" both ways (in some places as high as 5% each way if you exchange the wrong way).....but I digress.

For places I visit often I always keep some currency so the next time I go I don't have to worry about converting money as my first task.