"...The solution is to put industrial-strength spamming technology into the hands of ordinary citizens. The resulting deterrent effect would reduce the flood of spam to almost nothing, as no rational spammer would risk immediate retaliation in kind."
Meant to be a joke, but interesting nonetheless. Problems: the 'deterrence' effect would be nonexistent, because of aversion, and the fact that spam is a one-shot game (ie, you can get new email addresses). Link.