Freecall.com lets you make free long distance calls with the help of your computer. You can make a call from your computer to a land line or from a land line to a land line. By putting in your own phone number as the callback number Freecall will call your phone first then connect you to the person you want to call. This a great feature but also a little scary in that you can make other people call whoever you want (as long as they stay on the phone long enough for the second person to pickup). The free service is limited to North America and certain countries around the world. See the list of counties you have to pay to call on the homepage.
I personally use Skype to make my computer to land line calls but thats only because I bought a year of Skype before I found out about Freecall. Ive tested both and find the reception to be the same.
Final word: Free alternative with Skype with its own feature set.