I haven't had a chance to use it myself, but based on the screenshots this plugin offers a simple way to select posts written and published on a blog, modify the layout and organization, and then automatically turn them into an ebook.
It offers nearly a dozen different PDF templates and it can create Mobi and Epub. While I don't much care for PDFs, that could be a useful option for more academic titles or a POD edition of your content. You can set the font, customize the PDF layout, and make other customizations before creating the ebook.
You can download the resulting ebook and distribute it to the ebookstore of your choice, or you can post it to your blog:
This is a useful plugin, but I wouldn't get your credit card out just yet. This isn't your only option, and some of the alternatives are free.
I think you should first check out Pressbook. This is a freemium service that can also help you turn blog posts into an ebook. It starts out free, so if you only need a single ebook then it could actually be more than you need. Pressbook also has a WordPress plugin so you can make the ebooks from your own blog. I haven't tried it so I don't know how well it works. And it is also the more professional option, IMO.
I haven't tried any of these plugins, unfortunately. As my regular readers can attest, this blog is usually rather flaky so I've generally avoided stressing it with unnecessary plugins (I learned my lesson with Onswipe).
Has anyone tried these plugins? I'd like to hear which one you think is best.