Dark Reader is a cool tool for those, who prefer to read the web in a dark environment. It offers to change websites to a dark version, that otherwise do not offer the option. But if a site does offer already a dark theme, Dark Reader offers users to opt out from altering an already dark site to it's dark version. It is also possible to disable darkening sites all together. The preview interface (which I can't wait to see fully implemented) also support dynamic switching to a dark theme.

The author faces many uphill battle to support this add-on, and the fact that they still provide support despite all the backlash is more astonishing then anything. May be biased myself, it definitely deserves a positive rating.