more control over email subject lines

This has been on my mind for some time now...it would be great to have a bit more more granular control over the subject lines IPB automatically sends out for things like comments, replies, etc.

For example: when a client replies to a project discussion thread, I simply get the title of the forum thread X in my notification email.  It would be a bit clearer if it read "Reply to discussion X" or "Comment on X" or something like that.  I think it would be good to change this, but even better to allow site owners to configure these things wherever possible.