Good post. This is approximately what I've been doing for the last two weeks as I try to contact specific developers to come work at famo.us. I spend time researching them, including reading their github code, twitter and G+ streams, LinkedIn, personal blog etc.

If I can't find a solid connection between what their experience and the things they love to do then that is a signed that I haven't researched enough or that there really isn't a fit and that I shouldn't bother them and waste their time.

My favorite quote about email comes from Seth Godin:

"I don't want to get email from anybody. I want to get me-mail"