I'm facing up with that question, who knows? Do other and bigger forums exist than MMG?

There are some other forums, but MMG seems to have the largest userbase, most content and discussions.

I see.. how fast are the forum developing, how many members are joining per day?

MMG is the best! :D

Not a clue, PM an admin, or wait for an answer

Yeah, sure, I will:))

If a bigger one does not come up in Google.... then there most likely isn't one.

Also, the price of the advertising is a little bit of an indicator.

Probably the biggest is Warriorforum.

Just scroll down to see how many are online right now (19,293 right now on WF)

After TG forum rotten with their fascist mods, certainly MMG and DTM followed by MFC and RC

it still have some other forum for HYIP =)