Are you familiar with Conjecture Corporation?

I've received an unsolicited job offer from them, through Mturk, and wonder if anyone knows anything about them? How would you handle a job offer that you got through Mturk? I'm a little hesitant, of course, but they seem on the up and up. The job is easy, similar to what I am doing on Mturk but more in a moderator capacity. It's a home-based job. My concern is submitting my Social Security number to them. There is a contract involved, which is no big deal as I can quit any time. It's that submitting of the SS# that worries me. But it's a good opportunity. I've talked to a couple of turkers, who seem fine with it, but I thought I would present this to a larger group, for more consideration. What would you do?