I think you're on to something here. I would like to have a computer that would send a 150K surge of high voltage back along the transmission path of spam and fry the cable modem of the spammer who sent it. Hopefully, the backblast would get the spammer as well.
The Cherenkov radiation produced by said surge and the sizzling sound made by the spammer's electrocuted body would be as entertaining for me as any network TV show.