No, I'm not talking about stealing carfax service. I just ran across this link. https://www.nicb.org/theft_and_fraud_awareness/vincheck They offer a free VIN check to look for salvaged or stolen cars. It's not a detailed report like carfax or autocheck, but it's free and could be useful when car shopping.
You can do the same thing if you have an ebay account. Just make a listing as the car that you are looking at and it has a free carfax. Only 6 per account though, so be careful. Then you can delete the post and the carfax will still be in your selling history.
Here's a site that gives you a free AutoCheck vehicle history report: http://motosnoop.com/your-free-vhr/