runouw.com

Following that logic:
100k: 3 yrs (i.e. 3 years after the forums were created, we reached 100k posts)
200k: 2 yrs (i.e. 2 years after we reached 100k posts, we reached 200k posts)
300k: 1 yr (i.e. 1 year from now, the time in which 200k posts were reached, we will reach 300k posts)
400k: 0 yrs (i.e. after we reach 300k, we will then instantly reach 400k posts)
500k: -1 yrs (i.e. 1 year before we reach 400k posts, which is now, when we reached 200k posts, we are also simultaneously reaching 500k posts)
600k: -2 yrs (i.e. 2 years before we reach 500k posts, which is when we reached 100k posts, we also simultaneously reached 600k posts)
700k: -3 yrs (i.e. when the forum started we had 700k posts and 0 posts simultaneously)

So... WOO!!! 500K POSTS!!!

Following more proper logic:
100k: 3 yrs
200k: 2 yrs (2/3 of 3 yrs)
300k: 1 & 1/3 yrs (2/3 of 2 yrs)
400k: 8/9 yrs (2/3 of 1 & 1/3 yrs)
etc.

So at this rate, it will take 1 & 1/3 yrs to reach 300k posts, and 8/9 yrs to reach 400k.

We've had 284 posts since then.