Wow, Skype is really great. I've heard good things about iChat, but of course, that only works on Macs. Yes, I know Windows users can install AIM, but I wouldn't wish that punishment on anyone. I was forced to try it because I am currently behind a very annoying, restrictive firewall, and OpenH323 was cutting out every dozen minutes or so. With Skype, the sound quality is better and the delay is noticeably less. As far as I understand, the reason that open source voice codecs are so much worse than commercial codecs is mostly because all the commerical codecs rely on lots of patents. I know that Speex have done some excellent work, but even their own codec comparison page seems to indicate that the proprietary algorithms are better, particularly when you look at the delay numbers. [Update 2005-03-31: I definitely misread the Speex codec comparison page. I've posted a clarification about Speex]