I've seen this a few times on different forums, for wildly different subjects.
There is usually a big boom in users, sharing ideas and swapping experiences. Then an accepted method becomes settled on and variations become unwelcome, eventually new users feel like their interactions make no diference to the accepted norms and numbers dwindle as existing users see nothing new coming in...
I think this is the life cycle for many forums, I've yet to see any re-invent themselves and hope this forum stays open minded and welcoming to new ideas and visitors.