You can report scams to your State Attorney Generals Office. Also, checkout these sites:
Yes. You can Goggle, enter "report scam or fraud".
If you've been scammed from an ad on Craig's List go to the ad and flag it. Craig's List will remove it. I believe you can also file a complaint at ftc.gov
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them