just a small one, shouldn't be too hard to implement either.
what about a possibility to turn off the message sound (that shhhh-ish one).

a few people asked me if this sound is "switchable", what do you think?

Renaming or deleting "message.raw" and/or "sysmessage.raw" in the snd folder will get rid of the sound.
But I guess an option would be more userfriendly. It has been suggested before though.