Trillian is basically a chat service: you use it instead of running AIM/ICQ/IRC/MSN/Yahoo/Jabber/other chat programs separately. I use Trillian and am happy with it.
What you may want to do is one of the following:
-Set up an IRC channel -- for this you'd need a host. I haven't done this so I don't know how.
-Create a unique AIM chat room -- for this all you have to do is invite yourself and others into the room of that name, and it comes back whenever people come back or are re-invited. This is really easy however for people who don't have AIM it's going to be inaccessible.
(For example: add yourself to your buddy list (if you haven't already) and right-click on your username, click "Invite to Chat Room" and type in room name "Abaisse" and if I'm online I'll be sitting in there.
I'm sure you can do the same with MSN or Yahoo but I'm not as familiar with those programs as with AIM. Yahoo does have chat rooms but I don't know how easy they are to set up. and MSN I just have no idea; I hate it.
You cannot set up audio/video chats on AIM. I'm pretty sure you can't either on IRC. I seem to remember Yahoo! having that option, though. (Although is it really necessary to have voice chats? It's nifty but I think voice chats work better on private conversations rather than public chat rooms. This is of course only my two cents.)
Alternately, I think
one of the goodies offered by my webhost is chat. I can check and possibly look into setting up a chat server on this domain. Don't know how well it'll work but it's another possibility.
...This is of course disregarding the web sites out there where you can set up a Java-based chat room.