2-step verification, if moderating spam is a problem.
I think most people would (or should) be horrified at adding to the stack of information owned by some company. Not being paranoid, or some conspiracy nut, just that I believe if I'm giving someone something, like data and their relations, beyond the bare minimum to have scrupulously-kept-discrete Facebook-space and Google/Android-space (not linked to any other sites like scribd or Amazon or pinterest, twitter, YouTube, or anything -- yeah, I know, it's a losing battle, but whatever), I want to be paid in cash. I don't believe in doing stuff for free, period. Just my policy.
For me, I just come here to chat about piano, not to network, make friends, or get money from impressions or click-throughs on a youtube channel or private website.