Everyone and their brother shops at Amazon.com. It is, after all, the biggest Internet-based retailer in the U.S., offering everything from books and apparel to food and jewelry. It turns out that Amazon is now cracking down on people who are posting phony reviews to the site. The latest case involves users of Fiverr.com, an online marketplace where you can take on such "gigs" as writing a news story for $10. Amazon discovered that people were offering to write positive reviews of products they'd never even used, often with text provided by the seller. Sometimes they'd go so far as to receive empty envelopes in the mail to create the illusion that they were receiving shipments of these products. Amazon is suing 1,000 people, but the most bizarre part of the story is that the internet giant doesn't even know their true identities. It has only user names to go by, and the fact these people employed multiple accounts and IP addresses makes it even more diffic...