Is there a way to block a specific website using Firefox?

[arabian]

I know there has to be. Can anyone link me to where I'd need to go to do so, or give me a quick run-down?

I really need to block a website for my blood pressure. I'm seriously not kidding.

One guess as to the website. (Revealed in comments.)

Comments

[arabian.livejournal.com]

Asswipe. Huh, I didn't even realize that about the mods' names. Typical of them. Totally typical.