I have made a plugin (my first public one) that allows you to run a mailing list on your blog. It has the following features:
-Users can sign-up to the mailing list by filling out a form
-Users can un-subscribe from the mailing list by clicking a link in the emails.
-Admin interface for managing users and options.
-‘Write email’ interface for composing emails to the users.
-Ability to email the mailing list, only the registered members, or a selection of members you choose in the interface.
-Ability to add recent posts to the footer of the email, any amount, and from any category/categories.
Visit the page (http://www.blue-anvil.com/archives/maillist-for-wordpress-a-mailing-list-mass-mailing-mailer-plugin) for more details/download link.
I would be extremely grateful if any bugs/errors were reported, as I am new to wordpress plugins and may have made mistakes.
I hope it is useful to you :)