You don't need anyones' MSN or Yahoo addy to chat immediately right in the group you are in now. You may not like posting your addy or ID for everyone to see, so this is a fast way to get to chat.
Just click on this link below, it will work with any MSN group. If you want to do this in another group, just type it right into your browser with the group name (at the end) you want to chat in, click "Go" & there you are! A small chat box will pop up at the top right on your screen. And if you want to chat again at a future time, it will be stored in your browser. Click your browser arrow and select the group addy from the dropdown.