There are many online resource websites such as IMDb, Rotten Tomatoes and Jinni that allow users to search for movies similar to ones they already like, find movies by actor or genre or even find movies by mood. Similarly, if users have a Netflix account, then Netflix will automatically find and suggest movies that other people with the same interests enjoyed based on a user's ratings for the movies that they've watched.
There are plenty of websites on the internet that are dedicated to helping users find things like movies, music, pod casts and art based on association. The way a lot of the movie websites work, such as Movielens, is that the user rates a series of movies that they've already seen, and the suggestion engine generates new movies based on those ratings. Some engines, such as Netflix, simply take ratings and suggest movies that others on the website rated highly. While these are good methods, sometimes users are looking for completely different types of movies and not just those deemed good by the general population.
The website Jinni allows users to search through movies through a wide variety of criteria that are not available on other websites. For instance, Jinni allows users to search for movies based on mood, setting and plot preference. Finally, Jinni allows users to search for movies based on semantic phrases, so users can just type something like "movies where things explode", and the website will be able to find a matching film.