We’re thinking more about this now that our API is nearing.
In the meantime, note that you can block any member from following you or posting comments on your content (look for the Flag icon on the member’s page).Aaron Tank commented
I agree that privacy settings are greatly needed. The ability to filter which activities are posted to my activity stream, to selectively remove activity from my activity stream, etc. I don't necessarily want every list I like and movie I add to my watchlist and review I post to be publicly posted in my activity stream.