Around 16 per cent of the complaints involved scams where crooks pretend to represent the FBI, while 11.9 per cent involved the non-delivery of merchandise or payment, the second most commonly reported allegation of wrongdoing.

419 (advanced fee fraud scams) ranked third with 9.8 per cent of complaints. Identity theft and overpayment fraud scams were also common causes for complaints.

Of these complaints 146,663 were referred to local, state or federal law enforcement agencies. Referred cases commonly involved financial loses, focusing on five categories: non-deliverey of merchandise and/or payment ranked (19.9 per cent); identity theft (14.1 per cent); credit card fraud (10.4 per cent); auction fraud (10.3 per cent); and computer fraud or hacking (7.9 per cent).

The highest median (average) dollar losses involved reported incidents of investment fraud ($3,200), overpayment fraud ($2,500), and advance fee fraud ($1,500) complainants.

IC3 takes complaints in many different categories including auction fraud, non-delivery of merchandise, credit card fraud, computer hacking, spam and child pornography. In addition to fraudulent federal agent cons, popular scam trends for 2009 included hitman scams, astrological reading frauds, economic cons, job site hustles, and pop-up ads for fake antivirus (aka scareware) software.

Read more here.