The problem:

As a Customer Service Representative or Support Agent, I want to be able to quickly see a prioritized list of open Cases on an Account or Contact.

Solution:  

First, create a couple of formula fields and lookup fields on Case and then create 2 Lookup Helper Settings.

Fields:

  1. Create two formula fields (text) on Case
    1. Account if Open:  IF( IsClosed = False,  Account.Name , Null)
    2. Contact if Open:  IF(IsClosed = False, Contact.FirstName + " " + Contact.LastName , Null)
  2. Create two Lookup Relationship fields on Case
    1. Account
    2. Contact

Lookup Helper Settings:

  1. Lookup for Account
    1. Select Child Object:  Case
    2. Maintain Existing Relationship:  Account
    3. Lookup Helper Setting Type:  Relate Cases when the value in a field matches the name/id of the Account
    4. Select field on Case to match the name/id of an Account record:  Account if Open
    5. Create a Setting Name, optional but recommended
    6. Save and Run Setting
  2. Lookup for Contact
    1. Select Child Object:  Case
    2. Maintain Existing Relationship:  Contact
    3. Lookup Helper Setting Type:  Relate Cases when the value in a field matches the name/id of the Contact
    4. Select field on Case to match the name/id of a Contact record:  Contact if Open
    5. Create a Setting Name, optional but recommended
    6. Save and Run Setting