One of HubSpot's top downloaded assets was a project I launched with them while at Aircall! It's a sales planning template. During our campaign period, we generated over 12k leads, globally. They host the asset on their site and see hundreds of organic downloads monthly. Check it out here:
https://offers.hubspot.com/sales-plan-template
I actually would love to see some innovation and freshness when it comes to comarketing! I've done all of the typical stuff (webinars, ebooks, content, discounts, bundles etc) and would love to see more B2B brands come together in more B2C style collaborations. Think about how Nike or Spotify collaborates with other partners and brands.