Alright, I looked over here and there are a lot of good ideas...
The group thing is a good idea, but how about this.
Everyone starts out as a Newbie. Once someone hits 15 posts, they will start getting unique titles.
By default, a user will go down the path of the Detective. However, this can easily be changed by going into settings.
I believe omitting game posts would be a bad idea. I looked on other forums with games and rank titles and most of them count posts in the game forum as "posts".
For this, like Kan-chan said, there can be a record of the previous organization you were in.
However, posts in different organizations can be counted separately, but will be merged into Active Posts when one sees a profile.
My idea for titles are something like this:
Detective:
Detective Boy (15+ posts)
Rookie Detective (30+ posts)
Experienced Detective (50+ posts)
Private Detective (80+ posts)
Senior Detective (220+ posts)
Master Detective (500+ posts)
Holmes's Greatest Rival (1000+ posts)
The Modern Holmes (1500+ posts)
Police Department:
Rookie Police (15+ posts)
Patrol Officer (30+ posts)
Police Officer (50+ posts)
Police Detective (80+ posts)
Senior Police Detective (220+ posts)
Inspector (500+ posts)
Senior Inspector (1000+ posts)
Police Superintendent (1500+ posts)
Black Organization:
Test Subject (15+ posts)
BO Grunt (30+ posts)
BO Assassin (50+ posts)
BO Agent (80+ posts)
BO Senior Agent (220+ posts)
BO Executive (500+ posts)
BO Senior Executive (1000+ posts)
BO Second-in-Command (1500+ posts)
For example, if I posted 1341 posts while a Detective, 244 while in the Police Department, and 948 posts while in the BO, then Active Posts would show that I posted 2533 posts in total. (of course, I don't have the time to do all that...)
But, if I was a Detective, it would show that I posted 1341 times when you look on the forums. If I was in the Police Department, it would show 244. If I was in the BO, then it would show that I posted 948 times.
In that case, if I was currently active as a Detective, my member title would show up like so:
Holmes's Greatest Rival (current organization's title)
Ex-BO Executive
Discharged Senior Police Detective
I think there should be other ways to say "retired".
For example, if one is a Test Subject, BO Grunt, BO Assassin, BO Agent, or BO Senior Agent, it would show up like:
BO Grunt on the run, for example.
But if someone was a BO Executive, Senior Executive, or Second-in-Command, it would be simply:
Ex-BO Executive
If someone in the police was a Rookie Police, Patrol Officer, Police Officer, Police Detective, or Senior Police Detective, then if they "retired", it would say:
Discharged Police Detective.
If someone was an Inspector, Senior Inspector, or Superintendent, and they retired, it would literally say:
Retired Senior Inspector.
If someone as a Detective was a Detective Boy, Rookie Detective, Experienced Detective, or Private Detective, when someone retires, it would say:
Rookie Detective off duty.
If someone was a Senior Detective, it would say:
Resting Senior Detective
If someone was a Master Detective, it would say:
Ex-Master Detective.
If one was Holmes's Greatest Rival, it would say:
Holmes's Greatest Ex-Rival
If one was The Modern Holmes, it would say:
Retired Holmes
So? How does it sound?