There's a little something something on Stanaphone, a WiFi phone for the Pocket PC that uses Voice over IP and gives you a hundred free minutes for calls to normal phones as well as calling cards for later. The whole things seems pretty simple and the author seems to prefer them to other services such as Skype, since you can receive calls from regular phones. There's no voicemail feature yet, but they seem to be adding stuff on a pretty regular basis. Best part is you get to have one number that follows you around, since you can just plug in a SIP phone when you're at home and use the same number. For those who don't use their cellphones for everything this could be a good choice.