I copied this from DB's FAQ section about user titles:
Everyone has a title within the forum. You will notice them below the Username in each post. Some titles are automatically assigned based on the number of posts a user has made, and some titles are assigned by the forum owner to denote official representatives of the company or other VIPs in the forums.

Here is the list of the standard titles and # of posts to achieve them:

0 Stranger
25 Newbie
50 Journeyman
100 Member
200 Enthusiast
300 Board Addict
400 Old Hand
500 Veteran
750 Threadhead
1000 Pooh-Bah
1500 GRAND Pooh-Bah

Hope that helps!