I set up a bare bones Linked In profile many years ago when I was job-searching. Never did anything with it, or paid any further attention to it. I have a avoided social networking (Faecebook, Twitter, etc.) like the plague because, well, I'm not that social.
A couple weeks ago I was idly looking for an old buddy of mine, and the only online contact info on him I could find was thru Linked In, so I reopened it to contact him.
Since then, my Linked In profile has been populated with HUNDREDS of "potential contacts" -- people who share some other contact with me, or some history (jobs, schools). Looking through the list I saw maybe a dozen names I recognized. People I havent seen or contacted in twenty years.
I sent a few of them invites to add me.
The other 400? Nope