AOL Instant Messenger
AIM is much like ICQ and it's one of the best choices to communicate with America Online users.
I seek you on of the most popular instant-messaging program that lets you communicate with peoples in real time. It also allow you to make PC-to-PC and PC-to-Phone calls, and send SMS messages for free to cellular phones.
Provided by Microsoft corporation, provide you with such services as PC-to-PC calls and dials from your PC to a friend's phone.
Relatively new instant messenger which provide you with standard features as other IM but also have some special features e.g. you can talk with people who is browsing same web page as you, you can also communicate with other IM such as Yahoo, AIM or ICQ.