For FireFox users, there is now an add-on that tell you of sites with malware. https://addons.mozilla.org/en-US/firefox/addon/3456
It also allows you to help them by rating sites along the way. You can help our site by rating it well. And,... tell others of sites you have had bad experiences with. Hmmmmm, I have one in mind. It just shows in your browswer as a small purple question mark and a click is all needed to do a rating.