You need to find someplace devoted to developing or modding MMO games. Everything I know about MMO engines I posted links to above (and below). There are a few forum members here that do play MMO games, but if they have seen this topic they apparently do not have any experience on the programming side.
Larian's RPG Chat forum may be useful for game design or feature discussion, but I don't think anyone currently following these forums can help with specific engine or programming advice.


DevMaster's Game and Graphics Engines Database - this site also has forums on game development

MMORPG Creation Packages

Game Engines (not specific to MMOs)

Modding an MMORPG ? forum topic

"Terra Nova is a weblog about virtual worlds."

Tobold's MMORPG Blog