Great idea! I suggest the following:

0-99 Posts: TSA Enthusiast
100-400 Posts: FlyerTalk Kettle
500-999 Posts: Economy Class Regular
1000-1999 Posts: Normal Human Being
2000-4999 Posts: Road Warrior
5000-9999 Posts: Time Waster
10,000-19,999 Posts: FlyerTalk Obsessive
20,000-39999 Posts: Person in Desperate Need of a Life
40,000+ Posts: Psychiatric Patient