Skype

It's not often that I get impressed by the latest 'hot' application apparently destined to change the world as we know it, but I have to say that Skype is damned fine (there was a time when I used to follow all the latest 'killer' tools, but those days are gone). Skype uses the Internet to make free calls between users, wherever they are in the world, just like a phone. There is no actual need for a phone, the only requirement is that both users have Skype installed and are online at the same time (plus of course they'll need speakers and headphones or a headset to speak and listen). I've tried it and it works nicely, though full-duplex it's not (talking at the same time is a bit iffy)...but BIG savings can be made on international calls...