Though I started playing with Skype a couple of months ago I did it primarily as an alternate video conferencing option to iChat. My family members in California running Windows never seemed to be able to get their video based AIM tools to work, yet once they installed Skype we were able to hook up quickly and easily. All was good and Skype became my occasional use tool for chatting with the family and a few Skype enabled friends.
The nice part about using Skype this way is that it's completely free. Skype doesn't allow you to call a land line for free though; for that you can pay as you go or set up a monthly account that gives you voicemail and unlimited calls (10K minutes) to various parts of the world. For access here in the US to any number in the US or Canada the cost is $2.95 / month. While you can't use it to place calls to 911, it's excellent for making a call wherever you happen to have a decent internet connection. That's what I set up - unlimited calls to the US and Canada.
The other option available with Skype is purchasing your own local phone number and having it tied to your Skype account. By doing this people with land lines can dial directly into your computer if you are running Skype. Don't have it running? The call rolls to voice mail, which you can see the next time you fire up Skype.
The calls to people through Skype—both to other Skype users or to people on land lines—are very clear. On my MacBook Pro I will occasionally get some very mild feedback if the volume is cranked up too high but it's very minor; a headset solves that problem. On my Mac Pro with a USB based microphone (and no video camera), the sound quality is excellent.
I've mentioned before that I'm a big LaunchBar fan. When you combine LaunchBar with Skype you get some great integration and the ability to call people very easily. Since LaunchBar can pull names out of my Address Book it makes looking up phone numbers and calling people very simple.
As an example, if I wanted to call my buddy Stuart I activate LaunchBar (Command-Space) and enter "stu". His name is displayed in LaunchBar from his Address Book entry. I hit the right arrow and then select his phone number (work or cell), then hit Return. Skype fires up and dials his number for me. This does take a little configuration to work properly out of the box; if you want to configure it yourself go to the LaunchBar help and search for Skype.
Additional LaunchBar Scripts for Skype
A gentleman named Dennis created a nice series of AppleScripts to control Skype from LaunchBar that really help out a lot. The ability to quickly call any number is there as well as the ability to hang-up the Skype call.
If for example I want to hang up a call I don't need to mouse over to the Skype window and poke at the red "Hang Up" button (unless I want to); I simply hit Command-Space and enter "hang", Return and the call is terminated. This is something I really appreciate while I'm using Spaces and the Skype window is in a different region than where I am working.
I now use this set up to make most of my calls. No more looking up a phone number and dialing it manually or burning up my iPhones minutes while I'm sitting at my desk. The other benefit is when I have to call an automated system that requires touch-tone entry I don't have to pull the phone from my face to see the keypad, instead I can use the nice big numeric keypad on my large Mac Pro keyboard.
I've always loved finding productivity boosters and this is one that has created a dramatic improvement in my ability to make and deal with voice calls.