Soooo... you witness an internet crime. Now what?
- If it is an international consumer protection issue, you might take it to econsumer.gov, which is a database of consumer fraud complaints ostensibly shared by 21 countries
- Interpol says "Criminal activity or missing persons should, in the first instance, be reported to your local police department or your National Central Bureau (NCB). " They maintain a list of specific agencies to report to.
- US Department of Justice (DoJ) has this page on reporting computer crime.