Hire from your user base
blog.alinelerner.com
blog.alinelerner.com
This strikes me as slightly creepy. If I give you my email as a customer, I am not sure I want that information to be mined for this purpose.
I mainly value my privacy about non-public information [e.g. lovers, close friends, current location] and that isn't acquirable without violating the privacy of my phone/email/etc.
Personally I use a different e-mail address for almost every site, so searching by e-mail address wouldn't find my account, but I know many people use the same e-mail address for several things.
Yes, I do understand people in the world don't all share my opinions given I was replying to the opinion you present. ;)
"You’ll probably want to find the person’s LinkedIn to see where they work and how long they’ve been there ..."
This is just lazy recruiting for people who don't actually have contacts and can't use those contacts to find good candidates, so instead they use social networking as a surrogate indicator of actual talent.
Bleh.