Yeah, I agree with the above post. It is not coincidence because the schools where I had regular contact with my potential adviser are the ones I got accepted into as well. In fact, when I was visiting one of them, all of the professors in the department knew I had been in contact with my potential adviser since the summer, and they complimented me for it. I think even if you send one e-mail just to introduce yourself and say that you're interested in working with someone, even if they don't respond (though that's usually a bad sign if they don't), it puts you an inch ahead of another applicant. Name recognition, that's the key.