Now some of these features you have to pay for, but the basic online chat (instant messaging) and online video and voice chat are free and the only requirement is the other party needs to be using Skype as well.
I've had a Skype account for some time but only used it while traveling many years back when I worked for Norstan/Black Box (I used it to do voice and video chat to my wife and boys while they were back at home). However, in January, I was looking for an alternative to my land-line provider, Embarq (whom was asking a whopping $15 a month for unlimited long distance calls) and almost forgot about Skype. I happen to listen to a few podcasts that feature people using Skype so I checked it out. I found their long distance plan was a whopping $2.95 a month so I signed up!
Sure there are limitations such as being tethered to your PC but there are Skype enabled phones you can buy which allow you to use it like any other phone in your house; all you need is the internet connection. You could even take with with you on the road and plug it into a friends house! For me a simple headset to my mac is working fine. I've even hooked up my wife with a Windows version of Skype so she can login as me and make a long distance call and not have to worry about long distance charges, cell phone signal strength, etc.
For something cheap and fast, check out Skype. Its a great alternative to your local phone provider as well as VoIP providers such as Lingo and Vonage.