Backstory: Micro communities are popping up in different niches. Brands are becoming defined by their customers and their interactions. Unfortunately a lot of these are held on facebook or other social media platforms where the brand owns almost none of the data.
The Idea: Community platform as a service.
Deep Dive: You would build a community platform, similar to a forum or discourse but allow users to customize and completely white label the experience. Your users would be able to track specific data points and interactions to provide a better experience for their customers. You would build image/video sharing, tagging and direct message capabilities, similar to what users experience on social media already.
As this gains traction, you could build a mobile app version.
Validation: Discourse is a good example of how a private forum can thrive.
Monetization: You would charge a monthly fee based on number of users.