Theoretically, 4-ch's simple post system should make it the biggest English-speaking forum in the world. (lol)
So, what makes a forum popular? Let's look at the most popular forums in the world for hints:
#1: 2channel. Popular because it stayed up while other anonymous forums went down; consolidated a bunch of different forums such as Ayashii World. The Live TV forums also probably contributed. There may be other factors which I don't know.
#2: Go-Gaia. Attracted little kids because of its avatar system. But that's not the userbase we want, is it?
#3: IGN+VaultNet. I don't know why this is popular, I don't know much about the history of this BBS.
#4,5: FaceTheJury and Nexopia. These are popular because you can just spam any damn message you want, it's like AIM. Maybe 4-ch should open a bunch of gimmick boards like 2ch has.
#6: Partyflock. Popular because it created a large number of forums to plan parties in different areas of the Netherlands.
#7: Off Topic. I don't know why this is popular, I don't know much about the history of this BBS.
#8: PaintBallNation. Popular because it created a large number of paintball forums and became the number one place to go for paintball.
#9: Something Awful. Popular because the $10 registration fee keeps out little kids, and because of its dedicated moderation team. Not popular because of some inherent superiority; go back to archive.org and see SA in 2002 if you don't beleive me on that.
#10: Fok.nl. I don't know why this is popular, I don't know much about the history of this BBS.
>>2 Now's your chance! Go for the kill!
>>3-1000 Discuss theories of attracting people!