A very nice feature for Stack Overflow (and other Stack Exchange sites) would be to indicate the number of notifications (if any) in the browser tab like seen on Facebook:
Of course that would require automatic update if content has changed. Some kind of 'push-notification' which would be a nice feature as well.
(Q|I|N) Stack Overflow
, whereQ
is the number of new questions,I
the number of inbox items andN
the number of notifications.