On the official Google security blog, staff engineer Niels Provos pleads:
Currently, we know of hundreds of thousands of websites that attempt to infect people's computers with malware. Unfortunately, we also know that there are more malware sites out there. This is where we need your help in filling in the gaps. If you come across a site that is hosting malware, we now have an easy way for you to let us know about it. If you come across a site that is hosting malware, please fill out this short form. Help us keep the internet safe, and report sites that distribute malware.
Google's anti-malware team is involved in an effort to identify all web pages on the Internet that could potentially be malicious.