Could we get a system where once a week or so, it downloads a list of all extra libraries and their version numbers, and if the local copy is out of date it downloads the new one?
I'd be willing to do it for you if you let me. I'd just need the API to check the version of the library (though I assume it's in the XML file) and we'd need a single location to store them in on the server instead of individual threads (I can also set that up as I know PHP)
Libraries are only available to licensed users. Therefore it is not simple to host them on a different server as it requires an authentication system which knows who is a licensed user and who is not.
The main reason that such a system is not available is software piracy.
Well I could authenticate it using the registration key.
it would download the list like
http://www.b4x.com/database.php?key=XXXX-1234
And it would be able to check your database to see if it's still valid.
(If it's not, I can even have it disable the auto-updater and suggest re-subscribing)