Check out Add-Art: http://add-art.org/ - "a free FireFox add-on which replaces advertising on websites with curated art images."

Here's a chrome extension that lets you toggle kittenification on or off. (It's not blocking ads yet-- I'll get that done eventually) https://chrome.google.com/webstore/detail/fgppoekgokpnoigpci... code: https://github.com/gk777/Kittens-Everywhere

Done. http://stanford.edu/~grantm/cats.html

It actually turns _all_ images into kittens, but I think it's an improvement. :-)

Here, this one will work without requiring jQuery:

  javascript:(function(){var a=document.getElementsByTagName('img'),i=a.length;while(b=a[--i]){b.setAttribute('src','http://placekitten.com/'+b.width+'/'+b.height);}})();

javascript: void $('img').each(function(i,img) { var $i = $(img), w = $i.width(), h = $i.height(); if ( w && h ) img.src = 'http://placekitten.com/+w+/+h;});

Paste that in foxnews.com!

    javascript:(function(){$('img').each(function(i,img){var $i = $(img), w = $i.width(), h = $i.height(); if ( w && h ){img.src = 'http://placekitten.com/'+w+'/'+h;}});})()

It was a pretty simple plugin.