Amazon.com: John G Faughnan's Home
This doesn't quite rise to the Freakononomics level, but I've written enough Amazon reviews to see a clear trend. My positive reviews are rated as "useful' far more often than my critical reviews. This may represent human limitations, but it's trivially easy for persons associated with a vendor or retailer to downrate critical reviews and uprate positive reviews. I'd say this qualifies as cheating an a reasonably impressive scale.
Of course when I look at a product on Amazon, I always sort so the most negative reviews are the top. I find that the "useful" attribute is ... ummm ... useless.
PS. Amazon did not post my review of the Digital Rebel XT -- in which I mentioned the rebate directions were rather confused. I think Amazon is getting more selective about critical reviews of top selling items. That's another sort of cheating.