Manually harvesting emails for an email list?

With all the recent email list threads starting, I thought of a few tactics I could use. Since everyone will be using squeeze pages and purchasing clicks from an email list, would it be possible to self harvest emails from facebook or something? You could obtain highly targeted emails that way. Would it be possible to load them into a mass mail list or something?

Would this be illegal because they didn't sign up for something?

Technically yes, it would not be legal. But this is blackhatworld.

Secondly, harvesting emails from facebook would be pretty difficult. It is one of the information values that people have to "ok" to be able to download. Meaning that even if you found a working info exporter (say from... a fan page), you probably wouldn't get their email address.

Maybe someone knows better, but that is to the extent of my knowledge.