Here are some very good fraud prevention and reporting resources. You can also use them to find out if a company is on the up and up before you send in your hard earned money.

Internet Fraud Complaint Center

The Federal Bureau of Investigation and the National White Collar Crime Center address fraud Internet  Fraud by providing an easy to use way of alerting the authorities.

ConsumerSentinel

An excellent international resource and online database with Internet scams and fraud information.  It includes the opportunity to file a complaint online.

The FTC's Bureau of Consumer Protection

Timely Consumer Alerts and more than 150 consumer publications.  Addresses credit, advertising, e-commerce and the Internet and other marketplace issues.

Consumer World

A big Internet consumer site, with over 1000 links to everything concerning consumers, including general information, complaint departments, and bargains.

SEC (US Securities and Exchange Commission)

General information describing various scams and how to protect yourself against investor fraud online. Includes information on how to complain or ask questions about investor fraud.
 

Findlaw

Links to the website of the Attorney General for each state.

Better Business Bureau - Register a complaint, check our an organization, or find a local BBB.

Privacy Rights Clearinghouse is a nonprofit consumer information and advocacy program. It offers consumers a unique opportunity to learn how to protect their personal privacy.