Advice about a nonprofit project

Hi guys,

I'm working on a nonprofit project. I have a blog, and I'm about to make an ebook available for download. I will not make any money on this, and I'm not trying to build a list.

I'm thinking of the blog as more of a hub around which my social media presence revolves....a place to send people who are interested in shorter comments on Facebook and Twitter to go to read more. I also think of Facebook and Twitter as my "list", because that's where people will be following me.

The ebook will be free--no requirement to enter personal information to get it--and can be redistributed in any way people like. It will have links back to the blog in it so that people who may have gotten it from somewhere else will be able to go back and have a look at the source, make comments, join me on Facebook, etc.

My question is--is anyone else using social networking like this? I would like to have an email list simply be another social networking button on the blog; this way if they're not on Facebook or Twitter they can add themselves to my email list for updates since they have no other way to get them. I installed a social bookmarking plugin for Wordpress, but it doesn't have anything like that (only an email button where they can email the content to a friend). The blog is www.pricelessearth.org, default Wordpress 2011 template. I'm trying to keep this super simple.