You already own the relationship.
This is what goes in it.

Payment processors and merchant-services agents

Your residual rides your merchants' card volume. When a merchant reactivates lapsed customers or collects faster, those dollars cross your rail — your income moves the same month theirs does. No other attach lines up that directly.

Accountants and bookkeepers

You already report the overdue invoices and watch revenue drift in the books. A service line under your firm's name — the invoices you report, collected — is advisory work with a counted result attached.

Software vendors with small-business customers

Your churn is mostly customers who never finished wiring your product into how they really operate. I close that gap — phones, calendars, intake, follow-up — and your at-risk accounts start showing revenue they can point at.

MSPs and IT providers

You bill these clients monthly already and you're out of things to add that aren't more helpdesk hours. This is a new line on an invoice you're sending anyway.

Manufacturers with dealer networks

You spend real money driving leads into a dealer locator and have no idea what happens next. A good share of what you paid for is dying in voicemail.

Distributors and supply houses

Your revenue is contractor purchase volume. A contractor who books more jobs buys more material, and your outside reps need a reason to be in the door.

Franchisors and multi-location owners

Royalties are a percentage of gross. Every call a location misses is your money too, which is why you'll act on it when an individual owner won't.

Associations and buying groups

Retention is the whole business model, and member surveys keep asking for something operational instead of another discount program.