Well to me it is confusing(Joking)....and you are completely responsible!!
Seriously....there should be consistancy in my opinion. If you start geographical, such as EastAsian or whatever you should stay geographical in major catagory. Not skip around from practice type to location and on and on. You know exactly what you mean and why but some are not that familiar to such nuances I'd guess as to why East Asian may be seperate from another form of Mahayanan Buddhism.
That is how I would do it...stay consistant in major catagory and then deliniate as considered necessary.
Or maybe you don't want to go by location...the consistancy of major catagory being the issue not the specific of how you want to portray it. It seems inconsistant right now, which for me(being very simple) confuses.

A real temporary fix from my simplistic point of view would be to replace Vajrayana with General Tibetan Buddhist forum, and fit in any leftovers into what is already on other boards of similiarity.
A general Tibetan Buddhist board...(and if desired) subforums of the specific schools, or just two subforums.... schools and practices. But a general major Tibetan Buddhist board being of most importance.
But what do I know. Feel free to take it with a grain of salt.
To add... a fair amount of peoples especially in the West just hear HHDL speak and may not know anything other than he is a Tibetan Buddhist. Not to play to the lowest common denominator but this gives newer peoples to Buddhism a general forum from which to go furthur. There are mostly a very educated crowd here but as the site gets bigger it will probably draw more from the general population. Maybe you want to discourage that...I do not know.
Now to get into your advertiseing......!!!
Did you know e sanga thread content would show up on Yahoo searches.....??
And did you start a Wikipedia page on this specific site yet? I do not know perhaps there is one.
I am full of ideas....mostly however of no import. Ah me what's a mother to do

"This order considers that progress can be achieved more rapidly during a single month of self-transformation through terrifying conditions in rough terrain and in "the abode of harmful forces" than through meditating for a period of three years in towns and monasteries"....Takpo Tashi Namgyal.