what are the best chatting programs?

I have used multiple chat programs in the past years and find that Pidgin is one of the best and easiest to use. Pidgin is a very small and fast program that allows you to communicate with users of multiple chat services. Pidgin supports MSN, AOL, ICQ, .Mac, XMPP (Google Talk and Jabber), IRC, Yahoo!, SIP, and a few other smaller protocols. Pidgin allows chat logging, which comes in handy if you ever need to refer to past conversations.

I recommend Pidgin over Trillium because Pidgin supports the largest number of chat protocols without having to use plugins. Trillium is another excellent chat program, but to fully use all the available protocols, you have to install plugins.

I also use Google Talk through my Gmail interface. Google talk supports AOL screennames, so you can chat with your buddies through the Gmail interface. To do this, simply enter your username and password in Gmail's settings page and you're good to go. While this does not provide the full chat solution that Pidgin does, it is available in most browsers, so you don't have to download an actual program. If you attempt to use the chat feature in Gmail from behind a company firewall, you may find that the chat port is blocked by default. To overcome this, you should attempt to connect to Gmail using a secure connection. Generally, this sends the chat traffic out a different port that is not blocked by default in most firewalls. So instead of http://www.gmail.com, try to connect to https://www.gmail.com. While not guaranteed, there is a good chance you will be able to connect.