a database, either for books or for movies.. maybe both
people create accounts. once with an account they pick.. their favourite movies(lets go with movies just for experiment's sake).
so lets say i pick "good will hunting" and "playing by heart" and "meet joe black", then marina comes in and picks "playing by heart" and "the matrix" and "a walk to remember". so now i'm bored.. i've watched all the movies that i know are good.. and i need something new. i go to the database and put in one of my favourite movies - "playing by heart" - for example, as a search. the search goes through the database and finds all the other people who chose "playing by heart" as a movie they like, then it lists all the other movies that they like sorted by the popularity of these movies among the people who have picked "playing by heart" too.
this way people with similar tastes in movies may share their.. experiences. maybe i'd have reviews in there, too.
amazon does something like this.. but maybe without the popularity rating. ack...
so, any ideas? suggestions? requests?