I have encountered what may be a relatively new fallacy, but is a logical fallacy nevertheless. A commenter attempted to argue that the Intelligent Design book Darwin’s Doubt is weighty because it has more 5-star reviews on Amazon.com than 1-star reviews. That is pretty surprising, to be sure, even given the inevitable turnout of the Uncommon Descent crowd. But it is still a fallacy nevertheless.
The quality of literature is vouchsafed by the number of stars a book has on Amazon.com; that accuracy of contents and rigor of scientific procedures used even less so.