Peerio is getting out of the gate with a nice bang. They are the latest in the P2P VOIP space, but unlike Skype require no connection with the network other than through the other users. Skype requires the connection to ping the directory server in order to properly list you in a friend’s call list. Also unlike Skype there are a boatload of features with the PC to PC calling like Voicemail and quite a few others. PC to PC is free and Peerio currently works on Windows and Linux, with Mac coming soon.