I finally downloaded Skype for OS X yesterday. It allows you to make VoIP calls to other Skype users anywhere in the world for free. It does require signing up for a Skype account, but that's really easy. Convincing family and friends to sign up too will be harder, but it's worth it since Skype is for many platforms and you can also send instant messages if you don't want to talk. The Logitech USB headset I have has great sound coming out of the ear pieces but the microphone isn't good. Making adjustments on my computer hasn't worked either, so I need another headset (only USB).
The only calls I've made are to echo123 and echo-chinese, the Skype testing accounts for English and Chinese speaking users. They're just answering machines that let you test your sound setup, so I have no idea how good it is with real people. Everybody who's talked about Skype says the sound quality is better than on a regular phone and other VoIP software.
For a price you can call landlines too, perhaps a good idea if you're unhappy with your phone company. I don't think I'll use this much, but if you travel a lot (with your computer) it's probably a good product for you.
