I have been using this ALOT since I discovered it about 6 weeks ago. You can make free calls to an actual phone (cell or fixed line) the only catch is they limit the calls to 5 minutes and even then you can just redial. If you are like me and have to call your host quickly or want to say a few words to friends or family then you should find it useful too.
Check it out at
http://www.icall.com