There are many instant messaging out there.
AIM, GTalk, MSN are essentially the same some can do video and audio all essential you can type.
Meebo can unified AIM, GTalk, MSN together all in one place and is web based, meaning it works from your browser NO Installation is required. So if you are at a friends computer or library you can access Meebo and all of your Instant message programs.
Some you can connect to your cell phone
Put some code on your web site so when you are on line they can see you are … pretty scary huh? I am register with all these services as RonSattar feel free to contact me.