how to add like button under every post excerpts?

Is it possible to add like button under post excerpts on home page?

Or is it possible to add fb like button on WordPress comment? So people can rate comments.

For example please see attached image:

There are numerous like button plugins at Wordpress Extend, like for example http://wordpress.org/extend/plugins/like-button-plugin-for-wordpress/ or http://wordpress.org/extend/plugins/fbog-ilike-button/.