Since I will soon be writing about travel on this blog, which will be unrelated to the rest of the content, I have written a small WordPress plugin that allows visitors to hide categories they do not wish to read from the site. This was a good opportunity to get some experience writing WordPress plugins too, the API is pretty easy to use.
The plugin is currently active on this site as you can see from the show and hide links in the categories sidebar. It works for hierarchical categories too.
The code is available at GitHub along with a list of current and planned features.
See the page in the WordPress plugin directory at https://wordpress.org/extend/plugins/selective-reading/