I have been thinking about the same thing.
I have been trying to figure out a way to admin access control through web interface (with database backend) instead of going through file permission.
One way that I can think of is using session (include in all file header) to keep track registered user login and force all download link to php download script.
The problem with this is, if they know the physical file location they can still go to the web address directly bypassing the session.
The session technique mentions above only protect php scripts. It may need quite some effort to maintain files download through php download/redirection script on a whole site.
Is there a good way to set up a restriction to a folder (and its childs) to allow access only to registered user in database.
I'm talking about direct file access (such as *.zip file).
It seems to me that .htaccess would be my best bet. Anyone have know a good tutorial for using .htaccess for Apache windows?