I have a link on my Twitter and Facebook accounts. I have a service setup so when a new person follows me I auto DM them with a link to check out HubPages.
Sometimes I tweet about it. All my links have trackers of course.
Often when I backlink a new hub I put a tracker into those links too should they decide to register. I have emailed family and friends and told them about HP too.
Out of 80,909 total hub views 17,417 were tracked views via my URL trackers, about 25% of total traffic. Only 5 users have signed up. Only 1 has actually wrote any hubs. This one person no longer seems to be active or is away for a while.
Point is its hard to get referrals of people who will actually write hubs, at least for me. Good luck