I've always thought it would be interesting for someone to build blockchain and ownership tokens into the very structure of a community platform. It wouldn't be too complex - simply replacing the gamification engine (used to give people ranks and points based on quality and quantity of participation) with a tokenization engine. Everything else -... See more

Probably the most popular by number of installations is the VBB open source software (Virtual Bulletin Board)

 - Khoros (fka Lithium) - Samsung, Sephora, Microsoft, Airbnb, Powerschool, eBay, Etsy  - Higher Logic (Acq. Vanilla Forums) - Tesla, Electronic Arts, and a lot of nonprofits. They also have good onboarding - Salesforce Experience Cloud - Farmers Insurance (Agents), UC BerkeleyAnd there are a few new entrants that might be interestingPayments... See more

Here are the leaders by market share, with a few example brands for each:

There are actually about a dozen platforms designed to fill this need - and they make up about a $2-3B annual market for brand community platforms today. Community-building is nearly as old as the internet, and so much has been developed since the advent of message boards and forums. 

Attendance/participation at events

Lapsed members or those who are at risk for churning

Power members/top advocates

Engagement over time