There are a lot of articles revolving around Laravel 4 specifically that try and explain how to abstract logic away from your controller, but most of them either kinda miss the point or overcomplicate things (by using facades, repositories, interfaces...).

Repositories have their place in applications that deal with fetching stuff - either if it's from a database or an external source. In the Laravel world the repository pattern has been praised a bit too much for its advantages in terms of testability and architecture. I've written about how you can achieve the same level of testability without repositories, but sometimes repositories really are recommended.