Skype is simply marvellous! we use it every day to speak with dear ones on the other side of the world. Yes, it needs our PC on, but in these broadband days, that's no problem, it's on all the time.
The beauty of it is that we can be walking around the house and still call out in conversation, just as if we were in the same house together! Fantastic. And it's free!!! Woohoo!! We can send IM too if we're 'out', also send files. Much better than MSN.
Drawback: I can't call ya Crumpet 'cos I need your Sype call sign!!