My late grandfather used to tell us that in our lifetimes we'd be able to talk on the phone and see the person we were talking with.
A few minutes ago, my computer announced that I had an audio iChat invitation from his daughter (my 87-year-old mother) in Florida. I answered, and she was just thrilled to have discovered what is essentially free long-distance phone service. (She'd "called" to tell me that her new Kensington mouse had arrived.)
If my mom gets an iSight camera (such as I have) we will have free video conferencing -- just the service her dad predicted.
For anyone wondering what on earth I'm talking about: iChat for Mac OS X is a free download from Apple. The text instant messaging and audio versions work with Mac OS X; to use the video version, you need the latest version of Mac OS X, v10.4 "Tiger" and a webcam like the iSight. To IM or conference with iChat, log in with an AIM account name or create a trial .Mac account and log in with your .Mac account name. You get to keep the name and use iChat even after the .Mac trial expires.
iChat instant messaging is also great for exchanging files. You can drag and drop graphics or text files right into the message field of your chat and the other person can open them immediately and discuss the contents with you. I use this technique quite a bit for reviewing layouts with graphic designers.