@ Overreactor- I agree that calling cards and prepaid international plans are the cheapest option, especially if you primarily use a cell phone. I have family in Jamaica and Japan, and making calls to these family members can be quite expensive. I can usually make the same number of calls for $5 with a prepaid card as I can for $30 on my cellular plan.
I would like to point out that making some international calls is as simple as making a domestic long distance phone call. When I call family in Jamaica, I simply dial 1 for the country code, 876 for the country code, and the seven digit local number. It connects just the same as if I were calling New York City or Los Angeles.