We have had a few situations now where we have needed to send out a newsletter to all our users, only to find that non of them have bothered to sign up to it!
So like true marketeers (were not really!) we wanted a way to have our users signed up to the newsletter automatically - whilst still giving them the option of un-subscribing.
The module is pretty simple, and currently only works on Drupal 4.7 - although we will put together a v5 release pretty soon.
You may also want to check out our article on adding your existing users to the newsletter subscription.