Get to know whether a site is free of viruses and spams

Not every Google search you do everyday contains a site that is completely safe.For example,it has been found out that the first google search page that opens up when you enter keywords such as Keygen and Free Screensavers contains all unsafe sites!!.
Fortunately,there are counter measures for this problem.
Following are a few services that help maintain you system free of viruses while browsing the web.

1. 
   WOT is a browser plugin that installs as an addon,and returns results of websites as you perform a google search.Below is an example preview of WOT.
   
   
   
   
   
2. 
   
   SiteAdvisor by McAfee does the same task as WOT,but with different symbols(Obviously :D).Below is an example preview of Siteadvisor.