To make your search experience more personalized, Google begin offering "blocking the sites" you don't want to see on google.com in English for people using Chrome 9+, IE8+ and Firefox 3.5+.
Begining today, when you Google, 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. The link is visible to all, but to block the domains, you'll need to login to your Google Account.
Once you block a domain, you won't see that in your future search results. The next time you're searching and a blocked page would have appeared, you'll see a message telling you results have been blocked, making it easy to manage your personal list of blocked sites. This message will appear at the top or bottom of the results page depending on the relevance of the blocked pages.
You can see a list of your blocked sites in a new settings page, which you can access by visiting your Search Settings or clicking on the "Manage blocked sites" link that appears when you block a domain. On the settings page you can find details about the sites you've blocked, block new sites, or unblock sites if you've changed your mind.