Sample code to query related records //Suggested Wiki Update

[bdJohnson72]

If we need our query to include related record data we create an instance of our parent selector. In this case, Accounts and provide the query factory with the relationship.

 public List<Contact> selectWithAccountData(){
        fflib_QueryFactory contactQueryFactory = newQueryFactory();
        new AccountSelector().configureQueryFactoryFields(contactQueryFactory,
                Contact.AccountId.getDescribe().getRelationshipName());

        return Database.query(contactQueryFactory.toSOQL());
    }

Running this query will generate the following query string:
SELECT Account.AccountNumber, Account.Id,
Account.Industry, Account.Name, Account.NumberOfEmployees,
Account.Rating, AccountId,
Email, Id, Name, Phone, Title
FROM Contact
ORDER BY
Name ASC
NULLS FIRST