I’d like to set a weekly email blast to the subscribers of my blog which would include new content from the previous week. I’ve seen a lot of plugins for WordPress.org, but nothing for the WordPress.com blog I have.
Then on your main blog publish a post announcing newsletters and asking users who want to receive them to subscribe to such a newsletter to use the contact form you have created. When they use the form provide the URL for the new newsletter blog. Do be aware that the email addresses users leave for submitting commenting purposes are only for that purpose and not for any other purpose. In Canada using them for any other purpose is against the law. http://en.support.wordpress.com/contact-form/