"Big-Boards tracks the most active message boards and forums on the web."
That is hardly true.
"Big-Boards tracks the most active message boards and forums on the web, that have been submitted and approved for display on thier site"
That's more accurate.
Further, the number of posts they have listed is "historical", not current. Take a look at some of the post counts listed for these boards, then look at the actual post numbers. Does it add up to you?