1. Auction Fraud

The setup: Online auction fraud accounts for three-quarters of all complaints registered with the FBI's Internet Crime Complaint Center (formerly the Internet Fraud Complaint Center). There are many types of eBay chicanery, but the most common one is where you send in your money and get nothing but grief in return.

What actually happens: You never get the product promised, or the promises don't match the product. The descriptions may be vague, incomplete, or completely fake. One scammer accepted bids for Louis Vuitton bags that she didn't own, and then scoured the Internet looking for cheap knockoffs that cost less than the winning bid. She managed to collect at least $18,000 from bidders before she got nailed. A buyer thought he'd purchased a portable DVD player for $100, but what he got instead was a Web address for a site where he could buy a player for a $200 discount. The stories are virtually endless.

The risk: You get ripped off, losing time and money. If you spill the beans about the scam, the seller may retaliate by posting negative eBay reports about you using phony names.

The question you've gotta ask yourself: Who in their right mind would sell a $200 bag for $20?