Zenofon is a great service. They give you 20 USA numbers that you can forward to your contacts international numbers.
Its better than a calling card because instead of having to dial an access number, a PIN and then the international number, you only have to dial one local number which Zenofon forwards all the way overseas.
They also have a great referral system based off of the ancient Greek philosopher Zeno of Elea.
You can join Zenofon by using the link below: