(Sept 2016) Obviously I'm looking for some thumb in the air estimates as this isn't a 'knowable' figure. If we look on say the reddit it has ~5800 subscribers which gives us a rough ballpark for the community. Is there anything other smart way to guesstimate it?
Here's an analysis I did of the monero thread on bitcointalk in May 2016:
You have to figure that the number of posters/subscribers/users has gone up significantly in the last month or so though.