Idea: Browser Extension - DB Interaction

Take the browser extension(s) a step further by keeping persistent data. Store information from a page/session in either webstorage, localstorage, or a DB. Come back to the page a few days later (part B?), and see if the data can be retrieved from the db and change the webpage.

An example might be, add some interaction to a webpage like a dropdown list with some options to create a personal wishlist or reading list that only runs on Amazon [add a dropdown list to the amazon experience]. If you see book or item you like, you change the value of the dropdown (e.g., "Like", "Want!", "Must Have!!").
When you revisit the page at a future date, a query retrieves the saved information, and updates the current dropdown list for the current experience. Maybe even add a date stamp when it was previously changed.