Ghost is also missing a default commenting system. You can
easily add Disqus
as a commenting system with their embed code option.

Disqus is the de facto commenting system for a lot of sites and
Wordpress blogs out there. To get started:

- Select the Universal code

- Add the code on the next page to your clipboard

- Now open Cyberduck and navigate to your theme folder.

- Select the post.hbs file to edit with your text editor

- Add the code you copied from Disqus anywhere after the
{{content}} tag. So something like this (depending on the
theme):

- To have Disqus list the number of comments on a post, you need
to scroll down the Discus page and copy the "How To Display Comment
Count" code:

- Then you need to open Cyberduck and select the "default.hbs"
file to edit with your text editor:

Add the code in this file before
</body> tag.
- Then you need to head back to Cyberduck and select the
"index.hbs" file to edit with your text editor and modify the
"post-meta" span to have it look like:

(this code example is from the default Casper theme - if you're
using a custom theme, you'll need to figure out the best place to
add the comments link).