Personal Blocklist by Google
Sometimes when you do searching on Google, the results you get are not relevant with the keyword you typed. Most of the websites are just a low-quality website and spamming the search engines.
To block the websites from re-appearing in your Google search results, you can use Google Chrome extension, Personal Blocklist. This extension will block the domain and you won’t see it again when you do the searching in Google.
However, you can always revoke a blocked site at the bottom of the search results. You can also edit the blocked websites by clicking on the extension’s icon at the top right of the Google Chrome window.
But just want to let you know, when you block a website, the URL will be sent to Google for their further analysis. With that, they can provide a better algorithm and also use it as a potential ranking signal for their search results.
New Chrome extension: block sites from Google’s web search results [via Google Blog]