I would vote for a small yet useful add-on of sound notification that would come together with the visual red notification badge, when somebody answers or comments my question. This would free me from continuous checking the page at moments where I'm working on something else.
Some usability proposals:
- global preference setting per user within profile,
- a menu of three choices: no sound, subtle and strong,
- a feature available starting at a specified point threshold.
This kind of notification is provided on some webmail interfaces having large public, so I don't expect that to present any bandwidth issues by the polling requests.