I saw one longest post not in my forums but another. It was about couple thousand posts long. The start of the forums was actually very interesting and brilliant. the owner was using a plugin where if he puts [you] in thread, it displays the name of member logged in. For example if the thread title is "Hello [you]" the I will see it as "Hello Iron Hide" and you will see it as "Hello Fluffybunny" and visitors as "hello unregistered" 😉
We all were posting hi and got confused about whats going on. Now when ever a new user joins he relies to the thread, and thread comes into life again and we start making fun etc. Genius Idea!
We have our infamous Heartfang Chat thread, which I started over a year ago and just got its 111,147th post a minute or so ago. A marathon thread for sure.