As for websites there is something of an option for you.
I use Norton DNS (it's free). Sites are run through their servers first before loading on your computer.
http://nortondns.com/
From Norton:
"There are thousands of infected and fraudulent Web site lurking on the Internet, with new ones popping up daily. So how do you know if a site is safe to visit or a dangerous site that should be avoided? Simple. Use Norton DNS. It automatically blocks dangerous Web sites so you can surf the Web without worrying about getting infected or scammed.
Norton DNS - a safer and smarter way to surf the Web."
Clear Cloud does the same thing as I understand it.
http://clearclouddns.com/
I use Web of Trust
http://www.mywot.com/ and love it! In answer to the question asked, "How would you know before a bad site/file came in contact with your PC?" It would just be a way for you to have the lab test the site before visiting it. Firefox has a report suspicious website, where you can type in the URL of a site you want investigated and a choice of two radio buttons with comments from what I remember. Something like the following
Space for URL:
1.) I think this is a phishing website.
2.) I think this site contains viruses/malware.
IE 8 has this too, but you have to actually be visiting the site to report it, and that is something that is not good.
In the Avast UI you would have a tab or button that would say, "Submit Suspect URL/File to Virus Lab." Clicking on that tab or button, you are given the prompt to submit the URL or file from your computer that you want Avast to test. There would be a comment section for why you want to have the URL or file tested. The Avast team would have to decide whether to make comments for site or file submission required or optional.
Clicking the Submit button. The file goes right from the Avast UI for the user, to the lab for testing and the user's computer would remain safe.
The question that many have is this: "How else does this benefit the user?" Well, let's say that a user is testing a URL with URLvoid. URLvoid.com allows users to submit sites for analysis and do scans from daily multiple virus engines. Let's say that for some reason URLvoid.com reports that AVG picked up a suspicious site in its results, but Avast did not. (Certainly rare, but stay with me! hahahaha
) Let's say that Web of Trust gives the site that AVG picks up as bad, a red rating.
OK, AVG has said, "Bad site." WOT gives a Red rating to the site, but Avast hasn't detected it yet. So John the user wants to find a way to tell Avast about the site that is infected, but Avast in URLvoid multiple virus scan shows it as clean. The only way for John to tell Avast about the site, is he has to send an e-mail to virus@avast.com outlining that the URL needs to be tested and the evidence as to why it needs testing.
John should be able to take a composite of negativity about a site or file, open up the Avast UI, click on "Contact Virus Lab", type in the link or bad file and click "submit" for testing. Right now, the only way that you can contact the Avast Virus lab AFAIK is to already be the potential victim of a virus or threat that Avast has warned about. It would be easier to have the ability within the Avast UI to submit URL's and files directly to the lab. If the modern browsers can do this, if Avast could incorporate a feature like this, along with the upcoming Sandboxing in Avast 6, Viruses and Malware would be reduced dramatically.
Jack