this app called tango. with this app you can call for free over wifi or 3g and you call worldwide to anyone for free but here is the link to us and aus.
i do the podkast overlord podcast http://podkastoverlord.com/ and im going to post stuff like my fav app of the day and app of week like tango,voxer,path ill try to keep evrybody up to date with my podkast