We've been experimenting with unison.com. - easy sign-up. - no charge for outside vendors/clients/contractors brought into chats. - multi-threaded rooms (

We've been experimenting with unison.com. - easy sign-up. - no charge for outside vendors/clients/contractors brought into chats. - multi-threaded rooms (vs. one long chat). Web-based with native iPhone and Android clients (no native iPad client, which would be nice). Fairly simple web interface. Good feedback and integration into notifications.