By tracking messages, do you like the thing on old RPG where you could see if someone has looked at a private message? Or something else?

A post voting system thing has already been suggested, as has having some kind of reputation system (which logically would tie in to that rather well). I don't think Mahz has responded to the idea yet, however. Some users have said they dislike the concept, others have thought it good, but of course it comes down to what Mahz feels like doing.