How about writing a freeware system agent/daemon that would allow people to submit sites, and then everyone running that agent/daemon would automatically spider the site as one or more standard browser user-agents, so that the IPs would be different and couldn't be as easily blocked without blocking legitimate clicks. You could make it peer-to-peer and rate limiting so it wouldn't be blamed as a DoS attack client. OR allow it to do DoS non-rate limited attacks for some sites if enough clients feel that the site is nasty.