I'd like to build an asset listing page that I can use on multiple sites, nested within a page. I'd like this asset listing page to use the current site as the root node.
Any ideas how I can do this?
You could create a Folder and link all your Sites underneath it. Then set the Root Node to the folder. 
Wouldn't that list items in all the sites? I just want to list items in the current site. Here's the scenario. I have about 20 websites running on Matrix for our sub branches. I want to provide them all with a common admin interface. Each of the sites is a site asset, and they are all in one folder called 'sub branches'. I'd like for a person from any sub branch to be able to login to the admin part of their site, and have access to edit stuff that exists within their site - but not the other sites.
I'm happy with the permissions part of this - but I'm not sure how to build the admin interface that will list only files that are part of their site, in such a way that I can reuse the same admin assets across all the sites …
Sorry - I probably could have put all that in the first post!