You've probably had the experience where you've clicked a result and it wasn't quite what you were looking for. Many times you'll head right back to Google. Perhaps the result just wasn't quite right, but sometimes you may dislike the site in general, whether it's offensive, pornographic or of generally low quality. For times like these, you'll start seeing a new option to block particular domains from your future search results. Now when you click a result and then return to Google, you'll find a new link next to "Cached" that reads "Block all example.com results."
Once you click the link to "Block all example.com results" you'll get a confirmation message, as well as the option to undo your choice. You'll see the link whether or not you're signed in, but the domains you block are connected with your Google Account, so you'll need to sign in before you can confirm a block....
We're adding this feature because we believe giving you control over the results you find will provide an even more personalized and enjoyable experience on Google. In addition, while we're not currently using the domains people block as a signal in ranking, we'll look at the data and see whether it would be useful as we continue to evaluate and improve our search results in the future. The new feature is rolling out today and tomorrow on google.com in English for people using Chrome 9+, IE8+ and Firefox 3.5+, and we'll be expanding to new regions, languages and browsers soon. We hope you find it useful, and we'll be listening closely to your suggestions