Picture realtime IRC-style chat rooms on your mobile. an ongoing text conversation with an (n)-sized group of people.
Additionally, let's have mailing list style functionality from SMS. I can join a mailing list, or create one on an SMS listserv, and use one SMS to reach all the people on the list. I know you can keep lists on some phones, but that is different from a listserv where people can sub and unsub themselves at will.-- BunsenHoneydew, Apr 10 2004random, halfbakery