Someone should figure out a way to hack a tivo into an anti-ad box. Get it to detect phone numbers in tv-ads, then call them up with the built in modem and waste the telemarketers resources. Or maybe write a virus to infect everyone's Tivo (or pc with a tv-tuner card and a modem, heh) to make a concerted distributed assault on telemarketing.
It's just an idea. Nothing dangerous about that, right?