This website will let you make unlimited free landline/mobile to landline/mobile calls wherever you are in the world. It works like this:
Say I have a friend in Australia - I go and register his number on that website.
The website gives me a local UK mobile number which automatically forwards to the Australia number.
So to call my friend, I can now call a local UK mobile number.
I checked with my provider, Vodafone, and they said that this mobile number that this website has given me is *included* in my monthly minutes. (fyi, i was given an 07031 number which vodafone said is a standard uk mobile).
So if you have friends/family abroad, this is a great way to use your monthly minutes at no cost :)