It can be desirable to let clients (the people who pay me) have a look at the newsletter subscriptions.
A nice and flexible way to do this would be to make newsletter subscriptions available in Views. On the first page of creating a new View, in addition to "node", "user", "node revision" etc, one could choose "newsletter subscription" as the type.
This would allow to create customized overview pages or even RSS feeds or excel spreadsheet export. Maybe the client does not even want to use Drupal for sending out the newsletters, but still wants to use it to collect the subscriptions.
Of course there are some privacy issues, one needs to be careful that the View is not shown to anonymous users who will just leech the email addresses. But that's up to the module user (programmer/designer), I would say.
If this is too much work, it can already be helpful to make a permission for "view newsletter subscription", in addition to the "administer newsletter subscriptions".