Nuladion, you really did an amazing work !
I had no idea someone could achieve such a result only with php. Do you know if you're the first one to make something like this ?
I have a suggestion, maybe what I'm going to propose already exists but I don't really know about all these MOD things so you tell me: I think you should make a lighter version of your Quest MOD, simplify the whole idea, remove some of the RPG elements (shops, battles... maybe by using only your own script and not ADR) and focus on the communication aspect.
You were talking about a chatbox, could it be possible to let people talk to each other directly on the map instead of just using NPC ? Conversions would then appear in the forums as normal messages, each map would make a different forum, and every active day creates a new thread. It could be a new way for people to use forums ! Of course, some RPG elements would remain (like checking objects) and it would be possible to add the whole RPG action if one wants.
I really think your idea and work are fantastic, it's very simple to use, even with a poor PC configuration like mine, which is definitely a great asset. With some work you could create a new standard, I just think you need to focus on the communication aspect in the first place, to make it appeal to a wider audience and not only RPG fans.
P.S.: Oh, a question also: how about bandwidth, does it use a lot of it, does it require many queries to work ?