Safe Web surfing : Unsure About A Website?

There are a few online tools that can help you identify websites and determine whether they could harm your computer.

safeweb.norton.com
www.mywot.com
virustotal.com
with virustotal.com, you can submit a file of your computer you suspect is infected.

and you can install this tool too :
http://www.siteadvisor.com/
to see it in action :
http://www.youtube.com/watch?v=4Q82cne_7Hg