VoipStunt is a Germany-based service that allows free phone calls from your computer to landlines in a number of countries. After downloading the application and creating a user account, you can make 1 minute test calls – I did, and the sound quality is excellent.
There is a one-time “upgrade” of 10 euros which does not expire, so as you make more and more calls, they really become close to free. Almost too good to be true, and definitely beats the already low Skype-out calls, or the announced but not-yet-available Yahoo IM calls. Here’the link to the list of free countries, as well as rates to other destinations.