Make it possible for a directory listing, we'd make use of this in Apache:

Options Indexes

How you can list your directory content, including the default file that Apache serves whenever a directory is asked for i.e. DirectoryIndex index.html?

Ideally, we are able to set this up per virtual host. My vhost file looks something similar to:

<VirtualHost *:80>
  ServerAdmin my@email.com
  DocumentRoot /some/path/
  ...
  <Directory />
    Options Indexes
  </Directory>
</VirtualHost>

You can set the DirectoryIndex directive to some value, that may never occur like a filename in your filesystem:

<VirtualHost *:80>
  ServerAdmin my@email.com
  DocumentRoot /some/path/
  ...
  <Directory />
    Options Indexes
    DirectoryIndex !
  </Directory>
</VirtualHost>

But when somebody adds personal files named ! it will likely be offered by apache rather than showing your directory index. Therefore it is pretty much a strange workaround rather than an effective solution.