Unfortunatly, in doing so, I came up with either "definitions" of the concept or conspiracty theories about various organizations as "really a secret arm of blah" and other nutjobs.
What I need, is something historically found in Great Britain (This book is up in Scotland, but can stretch some) -- and I need two of them.
The one should be more on the side of Light and Freedom -- encouraging folks to find their own way -- but not likely to spread the "knowledge of old" to those not ready (which is most everyone not in their group). The second should be more on the side of Power and Control – Chaos is fine too – the group shouldn’t view itself as evil, rather more “guiding hand” as “the masses need it” kind of thing. Neither should want "ancient tomes" in the hands of "The Masses" -- but for very different reasons and willing to use very different tools/actions to accomplish their goals.
EDIT: My bad -- I hit the Wiki page on this topic, and am looking for something a little less widely known than the Free Masons and the Illuminati... (but thanks to the first 4 of you -- it's good info as I didn't mention this ;>)