McAfee SiteAdvisor
Here you'll find a free downloadable application that, once installed inside your own Web browser (it works with FireFox and Internet Explorer), aims to keep you out of trouble — or, to be precise, stop you from clicking through to websites where spyware, worms, and other cyber threats lurk. The program attaches tiny color-coded icons to links that appear on a list of search returns — a green check means it's safe to proceed, a red X means it's not; a yellow icon indicates nuisances such as spam or pop-ups. Why would you need this? Because simply clicking through to a suspect site can wreak havoc on a PC, and risky sites comprise a growing portion of search returns. If you want a service that will flag for inappropriate content such as porn, try Scandoo.