Bloggers can now add a Send to Kindle button to their posts which gives their readers the opportunity to send that post to their Kindle device/app to read later. For WordPress users, there’s a plugin for easy setup. Blogger users can create a widget, then copy the code to your site. Both pages have details on customization and installation.
From what I see in the instructions, this setup works best for blogs with “classic” themes. When the theme is highly customized, the widget/plugin will also require customization to insure the content sent to the Kindle will display properly.