Those of us with military experience would be quite confused by the order of ranking suggested above, as one doesn't find admirals and brigadiers (generals) in the same service, (they're equal rank), nor does one find admirals and colonels in the same service (army colonel = navy captain), and lieutenants are the lowest-ranking officers (equal to ensign).

I like the idea of including a ranking sytem in addition to whatever title is chosen by the user. That way we can see that user "LW Master" is actually a rookie with 4 posts. Incriments of 1,000? I'll probably never pass "rookie".

Other systems: apprentice, journeyman...
or plebe, bachelor, master, doctor, professor
or perhaps even cub, wolf, bear, lion, scout. (I must have had a thing for uniforms.)