Google has its own service to host free static web sites, it’s sites.google.com. Here you can only host static websites, this means that you have no animations, no comments and no ads. When I had my website hosted there, i decided to put comments under every post, but it wasn’t possible, as said before. Googling around for an entire day, i found this nice website, that makes you put an html box inside the page that enables comments. Here is the link to the page.
You just have to follow the instructions in the given link, and you will add comments to your Google site.
Once you’ll have installed it, the tool will create a box for the chat.
When you want to send a message for the first time you’ll have to login using social networks (ex. Facebook, Twitter, Google+) or registering via e-mail and you can write comments using this tool.
I hope this post helped you. In my eyes it’s a very cool tool and it’s compatible with various social networks.