No matter how much planning you do, most likely you will find yourself in the situation where you are almost out of money and are freaking out. I found myself in this situation after a few weeks in Spain. The 800 euros that I had brought with me had almost disappeared after paying a safety deposit, 1st month´s rent, and groceries every week. Our stipends still hadn´t arrived in our bank accounts, and my hometown debit card did not work in ATMs. Thus, I was on a frantic hunt for way my parents could send me money.
1.) Open an account with an international bank. Although there aren't many, there are a few really large banks that have offices in the U.S. and Europe. If you happen to be lucky enough to live near one of these banks in the U.S. and in your host country, this would be the best option. Your parents could deposit money in the U.S. office and you could withdraw it from the office in your host country (or with a debit card). Although this is the easiest and cheapest way to transfer money, Unfortunately, most people aren´t lucky enough to fit perfectly in this situation.
2.) Paypal.com. This is actually the one I use in Spain and the most convenient option for me. Creating an account is free, then you can register your bank account with your Paypal account. The verification of your account take around 3 days, but after that you´re ready to transfer. Your parents (or whoever is sending you money) have to also have an account attached to their bank account. All you have left to do is transfer the money from their Paypal to yours, which is quite easy and cheap (less than 3 dollars, I believe).
3.) Western Union. Before I discovered Paypal this is the method I used. And is a good option if you do not have a bank account in your host country. At WesternUnion.com you can find all the sites where you can send and receive money. One advantage is that once the transfer is entered into the system, you can receive it almost immediately. A major disadvantage is that it is much more expensive to send money each time (around 60 dollars). So if you´re going to use Western Union, I recommend sending large quantities at a time.
4.) Debit card that works internationally. Another option you have is checking with your bank before you leave to see if your card will work in the ATMs of your host country. It is also a good idea to let any bank or credit card company know that you will be traveling abroad, also where and how long.