Are there any anime suggestion engines? In the past, I've used apps that have suggested films, books, or music to me based on a set of items I've enjoyed that I provide to the app.

Is there anything like that for anime? Basically I'm looking for something in which I can input that I like anime X, Y and Z and for it to suggest that I might like anime A because it has similar themes, or because other people who like X, Y and Z have also said they like A.
Anime-Planet and MyAnimeList have user submitted suggestions for shows on a "if you liked X, you might like Y" setup.

As a developer myself, this is something I've wanted to look into making, and MyAnimeList seems to be the most common site to be used for an engine as they provide an API to programmers.

Anime-Planet Recommendations:

Per-show Recommendations:


Update:  Anime-Planet now have version 1 of a personalized recommendation engine that works off what you have already seen



MyAnimeList Recommendations:

Per show recommendations



There are a couple of engines based off of MyAnimeList that people have made such as AnimeRecs (which is down at the moment) or mal.oko.im 

There's also a new anime cataloguer Hummingbird which gives you a range of  recommendations based on what you've watched, what genres you like, which are your favourites. It seems to be the easiest to access and isn't soley show-specific.

Hummingbird Suggestions:



Other Sources
Other websites which provide anime have recommendations engine built in, Usually these are based off of what similarly interested people have enjoyed also.

Crunchyroll (Thanks @David_Starkey ):



Amazon: