The value of the dollar to other world currencies changes all the time. When my husband, Tom, first went to Japan 20 years ago you could get 145 Yen for every US $, now it is half of that around 77 Yen per 1 US $.
So this could be something to think about if you are thinking of traveling internationally. If you are on a budget, Japan probably is not the best place for you to visit at this time.
The chart here is the changes to the Euro/Dollar over the last year. If you take a look you will see that the end of April, was the best time to covert your dollars to Euros.
There are fees associated with currency exchange and they vary widely. Last time I found my local bank had the best rates and fees, which made it easy. Remember when you covert your $’s to include small bills for the new currency. You may have to grab a taxi or want to tip a hotel bell man and you should have (local) cash in hand. Also it is great to have the local currency of the country you are going to visit for emergencies or maybe you just get hunger!
One website I have found that has a lot of good curency information is http://www.xe.com/
It has been recommended to not get a lot of currency, just what you would need for three or four days. With debit and credit cards you typically do not have to have as much cash as you did years ago. Also in most places I would not take travelers checks. They are not as widely accepted any more and seem to be more of a nuisance then a help.
Be sure to research the currency of the countries you are going to. This includes the fees from your bank for using your debit/ATM cards in those countries.