That members can join and have a section which they can create. I'd assume someone would have to be in charge and then tell people what they can make, and where. That way the final product (if there is such thing in sc4) would basically a collaboration of what a bunch of us have done.
I saw something called 3 rivers region and thought that this is what it was, but after going thru the threads under 3RR it seems to be something else, I'm not sure? If it is, how could I join and make a neighborhood or something to be included in it?
Hello, welcome to Devotion, a neighborhood of the SC4 community. Along time ago, before Maxis stopped making the SC4 series to do their mild violent creature SPORE series, the Maxis official SC4 site had something similar to what you are talking about, where you could join in with online region squares.
The last time I saw something like that was considered a mayor diary on this forum, not that long ago, but I don't have the address, because there are so many diaries addressed. With all the custom content these days, the rules are involved and you have to be kept up with everyone else's plugins, but you also could not have a plugin in your folder that someone else did not have, unless you asked permission, and got approved.
You can probably play along with this group (http://sc4devotion.com/forums/index.php?topic=11945.msg367248#msg367248) doing a "multiplayer" region
The funny thing is, that was the group I was thinking of, but at the time did not have the link.
That group's development thread at Simtropolis is active atm, you may want to look at it. Link (http://www.simtropolis.com/forum/topic/40609-sc4-multiplayer-development-thread/).