AOL instant messenger, ICQ, MSN.

Or do what I do, get trillian and run all of them simultaneously with one program so whatever people use I can just send them a message on it.

o~o what's trillian?

Trillain is my preferred client, it's an instant message system that works with multiple messaging systems where you can make accounts for multiple things, bu then just run one actual program on your computer and just have one contact list that pulls everyone up. It's been useful rather than having to install a different program based on what each individual person uses.

okay well I downloaded Trillian and added my MSN account

Unfortunately MSN doesn't work anymore, but there are still IMs like AIM. There are programs like Trillian and...I think there was another one but I can't remember what it was called, which allows you to put various IMs into one. If that works the way I've heard people claim it works (I've never used it myself, since I only use Skype), you can have all your contacts from Skype, AIM, YIM, all different IMs in one place, and the design is, I think, customizable.

I used to use Pidgin to have all my contact in only one programs. But long time i really don't use at all so i don't know how it's working or how good it's now. There is AIM, Yahoo messenger and trillian like other people say.