The BBC has an interesting article on the types of profit that spammers can see in the field.
I often get asked how spammers can make a profit when so many spam emails are obvious scams. The answer comes from the fact that spammers can send out millions of emails with little cost, meaning that even an incredibly small number of people responding can mean they make money.
In fact, the article states that the bad guys are “turning a profit despite only getting one response for every 12.5m e-mails they send.”