Some months ago i ran in a mmo development video presented in googletechtalks channel on youtube. link
.There are talking about server structure, used scripts (math, quest,... ), why these not others, npc ai, npc scripting modules and much more. Anyway very enjoyable video and it is possible it can give some good ideas.
mmo is called Planeshift, homepage link here.
The beauty of it is that the game is opensource, source code is under GPL license, some parts is their own licence, but is mainly storyline, characters etc. license link here.
I havent tried playing for myself, so i don't know how good/bad is their pathfinding. The main idea of this post is, maybe it is possible to adapt some parts of their code to mangos? it could be a great timesaver.