MuteLinks makes use of the Firefox's built-in mute tab functionality and automatically mute tabs based on their URL. It has two modes, mute only Blacked list sites or "Mute by default" were it will mute all sites except the Whited list ones. Every time a new tab loads or changes URL, MuteLinks will check the URL and accordingly with the chosen mode will mute the tab or either un-mute the tab if it doesn't fit the criteria anymore. Examples of good criteria:

http://facebook.com/ - Mute pages like "http://facebook.com/" as well as "http://www.facebook.com/about/"
"http://facebook.com/" - Use quotation marks to mute a specific page, "http://www.facebook.com/about/" will not be muted
google.com - Mutes all http:// and https:// google.com's addresses
.org - Mutes all ".org" addresses
/.*moz.*/ - Regex support

It is also possible to mute all Private tabs regardless of the chosen mode and the Blacklist/Whitelist sites. Contributors: @freaktechnik - For guiding me the right way @Staisser - For spelling errors @vb7prog - For bug reporting