*update – if you are just reading this post, please read the comments, where HiddenMarket.Net responds *
Supposedly most jobs are filled without ever being advertised through an "insider network". I seriously doubt that it is anywhere near the level most people think. As a hiring manager my problem was always in finding high quality candidates – regardless of my network. Most good employees came from outside the network…
That being said, this site (which I signed up for) just doesn’t seem to even be real at this point. None of the profile information could be changed, many of the links were broken, etc.
And there are so many ads all over that I suspect it is just an advertising site. I may be wrong – but I didn’t see anything on the site that would convince me otherwise.
Until they clear the clutter, or at least get things working, I would caution you to stay away. If this site is real, then they aren’t ready for prime-time. And if they aren’t real, I just burned a single-use email address on them.