I like it when "Member since" or "Joined mm/yyyy" is listed next to the post.
It kinda helps when looking at the post counts. If someone has been a member for 3 yrs and has 500 posts I'll probably give them a little more credence than a member that's been active a month with 1000. I guess I just think super high post counts in short amount of time means that a lot of those posts are quoting a previous one and adding "+1" or just inane and not substantive contributions.
That's not always the case, but my general impression.
-K