Instead of just a average post of a members lifetime maybe a last X days where X could be something between 10-100 days. I've been a lurker member for many years and consequently my post per days is quiet low. It is really not reflective of how active I am posting.

Maybe in the users profile more elaborate statistics could be shown for those who wonder about such.

Maybe give the user the option as to which time frame be displayed in the forum postings.