Due to the paradigm failings of popularity metrics a whole collection of parasitic "Web 2.0" vote spikers have entered the field. For example (from the now defunct FriendlyVote.com):
Others are http://www.usersubmitter.com/, Spike-The-Vote, PayPerPost and a host of other public cheating clubs and a perhaps even larger number of hidden puppet masters tied into criminal syndicates.
There is nothing that any of these sites can do about the spamming since its endemic to their model of ranking. Popularity is fundamentally flawed. It encourages vote rigging and buying "friends" and, worse still, in contrast to "link spamming" there is no way to distinguish the sincere from the puppets, free thinkers from bought voters and individual voters from ballot box stuffers. In an era of large scale computer hijacking into "Botnets" these heavily hyped "Web 2.0" sites are welcome playing grounds alongside email spamming. Not only are the top sites manipulated but also the hit and access counts skewed to make it look like they are getting many more readers than they really are--- sites profiting, I guess, from the cheats.
Since starting IBU News I'm become quite appalled by the scale of spammers. This site is not even announced yet (and still in development) and yet we are seeing high traffic of spammers trying to post or (aimlessly) manipulate our ranking. The traffic from them is greater than any of the "normal" users accessing the site at this time. They are quite automated. One modus is to target sites using popular "Blog"/CMS packages (like Drupal). Not only do they seem to use hijacked domains for account registration but even generate fake news feeds to distribute spam through the back door of content.
A lot of mainstream content too is little more than embedded marketing. Some years ago I was asked to write an article for a special supplement on mobile computing to be bundled with one of Germany's most serious "establishment" newspapers. I was told by the editor "you have complete freedom but should not write anything negative in the article about the products as the companies are paying for the ad copy".
