shakacode/react_on_rails by Ciro Santilli 34 Updated Created
Uses Redux, while reactjs/react-rails appears to do that more manually
Live instance: www.reactrails.com/ with source at: github.com/shakacode/react-webpack-rails-tutorial Not the most advanced web-app (a gothinkster/realworld-level would be ideal). Also has clear dependency description, which is nice.
Oh, and the guy behind that project lives in Hawaii (Ciro Santilli's ideal city to live in), has an Asian-mixed son, and two Kinesis Advantage 2 keyboards as seen at twitter.com/railsonmaui/status/1377515748910755851, Ciro Santilli was jealous of him.