what are the options for an American seeking cell phone service in Europe to call the United States?

I use my cell phone to call a server in our house that connects me via VoIP. Then I only pay the local calling costs of my cell provider to call. There are also servies (in Netherlands, I have used something called 1649). They do the same trick..you call them on a local number, type in the international number you want to call, and they connect you for something like 1 cent a minute and you still pay your cell provider fees.