The other day I had the need to scramble text on a page so I could capture a screenshot and send it to someone without them seeing the page content. I looked around for a Firefox Add-On that would do it for me but came up blank. So I wrote this quick:
javascript:function%20scramble(el){if(el.nodeType==3){el.nodeValue=el.nodeValue.replace(/[a-zA-Z]/g,function(x){return%20String.fromCharCode(((x.charCodeAt(0)<97)?65:97)+Math.floor(Math.random()*26));});}else{for(var%20i=0;i<el.childNodes.length;++i){scramble(el.childNodes[i]);}}};scramble(document.body);
Give it a try on this page to see how it works. Warning! You’ll have to reload, because you obviously won’t be able to read the text once this runs!
You can drag this link up to your Links toolbar or into a bookmark to make it easily available on any page.