The X-Plane Support Wiki
We have an X-Plane support Wiki: http://wiki.x-plane.com/.
I’m not sure what will end up there eventually, but it will include some airplane development info, a lot of trouble shooting tips, and general instructions.
It will not contain scenery or plugin development info, as they have their own full websites.
I encourage you to edit the wiki and help organize – I am putting information up there as I think of it, but I need help editing it for organization.