I just saw my post count in another thread, and it was 1979 posts since I first joined. It's not a milestone I'm celebrating, but the fact that 1979 meant something to me... Hmm... Oh yeah! The year my brother was born. However, now, I'll be higher in the post count. Anyways, look at the number of posts you've made (when viewing another thread), and think of something that happened in that year, or just google that number and see what comes up! I've just done it. The Bee Gees and disco reigned that summer!
EDIT: Note: If your number of posts is beyond 2008 (or whatever the year is now) make it up, but somehow based upon what the previous person has said. Below, I said in 1991 the Dangerous Dogs Act was passed, so, the next person could say that in 4622 the Dangerous Daleks Act was passed... or anything, or look into the tea leaves in your tea cup and make a Nostradamous-like prediction.