The idea:

The books a person reads say a lot about them. Because people put so much thought into what to read, the books they end up reading are great indicators of who they are. So if you're looking to find interesting people to talk to, their bookshelf can tell you a lot about them.

Besides, who better to give you book recommendations than someone who reads the same kind of books as you?

Readsalike matches you with others who read similar books.