Hey, I know MC already has an IRC chat set-up. But if there's any interest on having a Shoutbox, I tossed one up here: http://www.minecraftsb.info/
It can be incorporated into any website on the side so you can easily chat and browse at the same time. I'll add the links to the Main site, Wiki, Blog, and IRC shortly.
Well over at another community I'm a part of, We pretty much have every form of communication there is. Ventrilo, IRC, Forums as well as multiple servers. People have different preferences as to what form of communication they prefer. Some Prefer simply using a shoutbox over other forms.