This script can filter out any number of sites from Google search. Initially though, it filters only one site: http://www.experts-exchange.com/. Also if it removes any site, it will add a line notifying you, on which you can click to hide/show the removed sites.

I wrote this script for the sole purpose of removing expertsexchange (yes, they could not choose any better name) from my searches. I'm fed up with Experts Exchange showing up on the Google front page. They trick Google by hiding the registration page from Google bot, but when you and I go there we will see 'Register to view the answer'. In my opinion it is an extremely dishonest and unethical way to conduct business. Probably Google will take care of this matter, but until it does so, here's a script you can use.

To add more sites to block:
Edit the script and add sites like this near the beginning of the script -
sitesToRemove[0]='http://www.experts-exchange.com/';
sitesToRemove[1]='http://some.other.site.com/';
sitesToRemove[2]='http://yet.another.site.com/';
...

You can check if the script is working by searching for the blocked sites in Google.