Tastekid is a very good recommendation engine where you can say a few things you'd be in the mood for but you have already seen, be they books, movies, music, games... and it will recommend you new things.
You can easy restrict tastekid's output to a single category of content.
Please use your own API key
It works with an API key that can be asked for on the website: http://www.tastekid.com/ask/page/api_request. You'll get them instantly.
Then the key limits you to 150 uses a day (so yeah I should cache more stuff). The location of the key in the code is in the two first lines, so just get in the workflow and it'll be easy. It's implemented in a manner that allows multiple keys to work around the 150 limit.