The biggest YaBB forum I've come across is
one that is based here in Russia. The last time I checked, the following is what I read:
Statistics for: Absolut Games
Russian video gaming discussion board
http://forums.ag.ru/Forum software: YaBB
Number of posts: 6144156
Number of members: 464120
Post per member ratio: 13
Posts last week: 7359
Alexa ranking: 1868
The 2nd biggest YaBB forum I've come across is
one that is based here in Germany. The last time I checked, the following is what I read:
Forum software: YaBB
Number of posts: 1263421
Number of members: 14526
Post per member ratio: 87
Posts last week: 0
Alexa ranking: 614500
On the note about a forum being the
"biggest" as it were, I think the number of registered members is far less relevant than the number of posts.
Or maybe most relevant of all is how often any given forum is updated. Certainly to those members, even if there are only a handful, a regularly updated forum will be very relevant.