PartnerPage! It provides the ability for partners to market themselves and the platform for clients to drive the integration connections without the barrier of a partnership manager. It also provides the capability for Partnership Managers to feature particular partners at their own choosing without the involvement of Marketing having to create a separate partner feature. Hit them up if you are not using them already!
Beyond that - co-partner case studies work wonders. Telling the story from the client's perspective as to how they could leverage both of your services together and derive value from the integration exemplifies to others what they can expect by working with both of you. A good example can be found here:
https://www.adjust.com/resources/case-studies/magic-tavern-smadex-ctv-advision/