Block websites from search results
Google has given users the ability to block websites from search results. Information can be found from google blog at Official Google Blog: Hide sites to find more of what you want
On the Google search screen, the blocking option is found to be next to "Cached" and "Similar". After confirming the block, the next search you make will give you a message telling you that a blocked site has been forbidden from appearing in your results.
The limitation is that you have to have a Google account to be able to do this and be logged on to your account. Blocked domains are linked with your Google account, so sites you've blocked only remain blocked if you're signed in. Users can see all their blocked sites within settings, and unblock them if they so choose.
Their used to be a similar option before in Google Search but I can't remember ever really using it before and I think this option is more powerful.
This really brings up point that my search habits has significantly changed in the last year as if I am researching something it's usually prefixed with "wiki" where the majority of other internet information comes from google reader, twitter or facebook