If you are the type of person that dislikes those little site specific icons, then this tip is for you. Favicons can be disabled completely in Firefox with a simple config change. Just type about:config into the address bar, and then filter by browser.chrome. You should see something similar to this: Set the value of these two preferences to false by double-clicking on them.

browser.chrome.favicons browser.chrome.site_icons

You'll have to restart Firefox, but the favicons will be gone entirely.

Personally, I love favicons, but this article was a request.