I just noticed the activity rating. Quite amusing. :lol
I did a brief search and I'm not sure how it's calculated but it
seems to be mostly about the post frequency. Unfortunately, it's
not an indicator of the quality of the posts. 
I was initially surprised that the activity rating of the Buddism
forum was so high until I remembered how often AEN posts. Now I'm
surprised it's not even higher. :p
I think Atheism is kinda low though. I actually think the post rate
is quite comfortable. It's possible to catch up on all the
posts.
Atheism
http://atheism.sgforums.com
pls contribute and spread atheism
Moderators: january. Activity Rating: 1.527
~ Buddhism: Wisdom Bliss ~
http://Buddhism.sgforums.com
Discussion, Sharing and Enquiries to the truths (Dharma) of Wisdom,
Bliss, Enlightenment and Liberation...
Moderators: An Eternal Now, sinweiy, neutral_onliner. Activity
Rating: 61.001
~*~Eternal Hope~*~
http://Christians.sgforums.com
Moderators: sillyme, Chin Eng, ben1xy. Activity Rating: 49.949