I know this is probably a noob comment, but I should bring this up.
You know, it is curtesy to say 'Hi' to a person when they enter the chat. You can see their post clearly as soon as they click 'enter'. Sure, you may be in a conversation, but at least take the second to say 'hi'. Most people that chat now are new, and not greeting them will make them feel even more out of place then they felt before. Also, you'll make the person look like some idiot and invisible. I am not saying this because it has been done to me (it has). I am saying this out of respect for the new people of this site that are chatting for the first time.
Like I said, this is probably (most likely) a noob comment.