Examples Of Intentional B2B Marketing Strategies?

I'm compiling a gallery of examples of interesting B2B word-of-mouth strategies and I've found a few types of strategies:

1. Refer a friend and get X in return, eg service discount, extended subscription, or other business relevant perks.

2. Using a Business Influencer first to trigger referrals (Seen multiple VA agencies, get tons of sales through people discussing Influencer recommendations on Twitter)

3. 'Powered by software name' with chat bots and blog platforms. Such as when other businesses use services with embedded branding it exposes that brand to all the business’s clients.

4. Companies that recruit a strong traffic source to drive traffic to other sources, eg. Etsy recruiting business owners, who tell their existing audience and therefore attract more sales and more business owners to use their platform.

I was wondering if anyone here knows of companies that do this well. Or maybe have some insights of this for their own business?