Odd coincidence department: anna of annatopia and I have been posting to a discussion thread here regarding spam in which I consider that a charge per email--maybe a nickel--might be a price people would be willing to pay to be free of spam.
I used to hate this policy at Compu$erve, and I doubt it'd be exactly popular, but I've considered the notion of paying to send email. I haven't fully decided in favor, but a *very* cheap fee--say a nickel a pop--assessed by the ISP probably wouldn't add up to much for ordinary users, but it'd add up for spammers who send millions. It'd be even more appealing if ISPs lowered their monthly service charges a bit to balance the fee, and if the money collected went into some sort of fund for general maintenance and operation of the Internet. I haven't thought about where businesses would stand--a large corporation might send enough emails that the price would add up too, but if you exempt businesses you risk exempting spammers by definition. As I said, I haven't thought this through, but it seems an interesting concept.
Not long afterward I notice this post at Ipse Dixit citing a Tech Central Station article proposing a small fee for email--about a nickel. The difference is that the TCS article envisions users setting up a charge to receive email, and senders ponying up "digital stamps" based on an ecash system similar to PayPal; if the digital stamp is sufficient to cover your charge to receive email, the mail gets through and pays you.
Both of these ideas have one thing in common...as anna points out in the discussion thread, spam is ridiculously cheap to send, and ISPs, business and individual users bear all the cost of handling, processing, evaluating and deleting it. Imposing some kind of cost on the sender seems to be the obvious way to make spam go away.