The ninth day of the "12 Days of Retool" series focuses on a Retool application that enables users to rank and share their preferences for Star Wars Episodes 1-9. This application utilizes Retool components like the List View and Table, as well as Retool DB, to display and store user rankings. It features JavaScript and SQL queries to dynamically load and save user preferences, generate unique identifiers, and aggregate community rankings. Users interact with the application by rearranging movie rankings through a series of buttons, and these preferences are stored in a database for community analysis. The application is described as a simple yet effective demonstration of Retool's capabilities, blending interactive UI components with backend data storage and retrieval.