specificclick.net spyware

I checked my history this morning. I noticed that every time I logged into my email account, a long string of numbers and letters with "specificclick.net" was inserted between all of my emails.
I did some checking and found out that it was spyware inserted by websites that used "Site Meter".

I went into my "preferences", deleted all of their cookies, and it looks like I'm in good shape. After reading up on Site Meter and specificclick.net, I see that I'll pick up their cookies every time I visit a web page that uses Site Meter.
I found instruction on how to block the cookies, but not for Safari. How do I block individual cookies?
I just upgraded to the latest version of Safari.