I use AIM for text chat and Skype for voice chat. AIM is definitely the standard for online communication, even though it tends to disconnect/reconnect frequently. Still, one of the best messengers available.
Few people here seem to prefer Yahoo. I like it best because you can leave a message for the other person while they're offline, and they see it when they sign in. AIM doesn't let you do this - unless there's a setting change I don't know about.
It looks like I should be signing into MSN to be totally accessible to clients who want to work with me. Hmmm....
Gtalk for random biz
MyspaceIm random friends that wont jump to facebook
Yahoo random biz and friends
MSN friends and some biz
AIM biz and some friends
ICQ very few biz peoples
FacebookIM friends
Skype biz and friends
POP3 shit email
^^^all in Trillian Astra, even pop3 and skype, trillian astra kicksass
All the major marketers use skype... it allows you to IM thru ALL the others. Although it used to be buggy, skype has gotten a lot more reliable over the past year.