Might turn into a new tool at some point that would tag these folks.An article at the Physics arXiv blog about what's called the "Internet Water Army," large groups of people in China who are paid to "flood" internet sites with comments and reviews about various products. Researchers at the University of Victoria went undercover to figure out exactly how these informational (or disinformational) floods operate, and what they learned (PDF) could lead to better spam-detection software.
I'd like to see a simple add-on to the forum software here that didn't let new users post links until they were approved by an admin.