Tinychat.com has a solution. Visit the website and simply press "start chat" and you're given a tinychat URL. Send that URL to whomever you wish to chat. They click and enter the chat room. You can send the link to a number of people and expand the chat room to any number of users. You can also click the user's name to send a private message, and export the entire contents of the chat to a text file or email. It's kind of like a virtual tweetup.
This could be good for quick conversations or, as a brand, to answer some customer service inquiries, solve a problem or just communicate faster with any of your followers.
I had some initial problems getting it going in IE, but they soon resolved. It seemed to work just fine in Firefox.