Examine layout of the various UI parts. In particular chat and the user list, especially making the chat wider if possible. Also, possibly add a shortcut to open a "full" chat window.
User list
show idle time on user list
give indication of when users are typing (maybe using mouse as well)
expand user list to show where (which object/document) people are and/or have been
Concept map
somehow annotate nodes to show what users are in a node or at least that it's being worked on