How can you use an ATM abroad without getting charged extra fees?

I have an account with CitiBank and when I used my ATM (debit) card abroad in a CitiBank also I was charged a fee whereas if I use my ATM card in the US locations of CitiBank I don't get charged....Can somebody tell me what banks don't charge fees for using an ATM of the same bank abroad.... Also, I heard about some Global ATM Alliance...where supposedly I think 3 banks (Deutsche, Bank of America and some other bank) decided not to charge customers any fees as long as they use the card within these 3 banks....is it true or is it only a rumor? Any other helpful hints would be greatly appreciated...Thanks