I don't know if you know but recently facebook allow apps to collect email addresses, if the user gives permission. However, most of them will press the Allow button because they are used to this. If you are having 4-5 facebook acc with few k real friends and you promote a viral app like a quiz app or top followers or something, you can retrieve and store the email in a list and voila...depending on how viral your application becomes, you can get even tens of thousandths of emails. What's the best part, is that you can get almost any kind of information of the user, age, what he/she likes, gender, city, university, relationship status and so on and store the email based on this characteristics. You end up having a list of super targeted emails , but the problem is.. it's BH What do you think?