Code:
javascript:(function(){function R(w){try{var d=w.document,j,i,t,T,N,b,r=1,C;for(j=0;t=["object","embed","applet","iframe"][j];++j){T=d.getElementsByTagName(t);for(i=T.length-1;(i+1)&&(N=T[i]);–i)if(j!=3||!R((C=N.contentWindow)?C:N.contentDocument.defaultView)){b=d.createElement(”div”);b.style.width=N.width; b.style.height=N.height;b.innerHTML=”<del>”+(j==3?”third-party “+t:t)+”</del>”;N.parentNode.replaceChild(b,N);}}}catch(E){r=0}return r}R(self);var i,x;for(i=0;x=frames[i];++i)R(x)})()
IE and FF: Paste into address bar and enter.
Chrome:
Drag this link on this site into your bookmarks and press or paste into address bar or enter.
It's best for Chrome, as if you enter an annoying site with loads of ads but good content they can be removed quick and easy. Google Chrome doesn't have many proper plugins yet, enjoy.