It would be great if the Roku platform offered a "scrobbling" interface for developers to use in tracking watched content.
This would support cord cutters who want to keep track of movies, tv episodes etc. they've watched.
This would allow services used by cord cutters to provide apps such as trakt.tv, justwatch, reelgood, etc. to provide Roku apps that integrate with user accounts to record watched episodes, movies, listened songs, etc.
Scrobbling has been supported on Android, for example, for a long time so that apps like last.fm can keep track of and publish your listening history on various music apps.
One possible solution could be to allow users to turn on scrobbling, which sends all watched content to Roku servers, which in turn provide an API for any other app developer to access and ingest data for authorized user accounts.