State Attorney Generals offices: File a complaint in the ripp-off's state State Attorney Generals offices: File a complaint in the ripp-off's state
The Federal Trade Commission: File with these nice folks!
The National Fraud Information Center: File a national complaint with a national database
US Postal Inspection Service: Did you send a money order or check via US Mail?
The "F.B.I." Federal Burear of Investigation: File a fraud complaint! 
The Internal Revenue Service: Let them no you paid the ripp-off :-}
Computer Crime & Intellectual Property: Have you found your software 4-Sale on eBay??