Chrome: With more and more of us feeling that Google's search results are less useful lately, you can help yourself improve them with Blacklist, a Chrome extension that prevents spam search results from ever showing up again.
Search Engine Blacklist is so easy to use it's almost silly to explain. Like any Chrome extension, you edit the options by going to your extensions settings and choosing "Options" under the extension you want (in this case, Search English Blacklist). From there you can add in sites that you don't want to show up in your search listings. Add as many as you want, and you won't be bothered by their presence during future Google searches.