Above and beyond the ability to users / administrators to create groups and chat with one another... the money makers (plugins) on any social network platform are:

- business directory (with business review system, e.g. star rating system with comment section)  

- classified ads ( aka Market Place)

- placement of 3rd party ads or an admin administered ads placement system 

- dating platform

- this one is a bigger job, I suspect, setup to allow individuals to create storefronts  and a choice of their 3rd party payment processor(s) 

- etc.

I'll eventually start a new post of each of the above suggestions if there aren't suggestions for one already