Shoutbox

I think this would be a great feature, because it's quite annoying if people keep adding you to grouped conversations. It goes like this. When someone invites you, you get a pop-up message with:
"<username> invited you to a grouped conversation. Here is a list of participants in this conversation.
<list with users and their e-mails>
Would you like to join this conversation?
[Yes] [No]"
It would also come in handy if there is a person in the conversation who you don't want to talk to.