Add-on WOT Web of trust
A great add on for Firefox, Internet Explorer and other browsers, WOT warns you when you visit a questionable website. Green for good. Yellow for caution. Red for be very careful. You can bypass the warning, if you choose. Most search engines will show the symbol before you even go to the website.
You can rate the sites yourself. Unrated site are coded gray till WOT issues a rating. You will need to search for WOT for IE, to install on Internet Explorer. For Firefox, just go to tools, add on, do a search for WOT then install. I love it!