> web pages able to eat all my cores

We're already there:

    var code = "while(true){}";
    var Blob = window.Blob;
    var URL = window.webkitURL || window.URL;
    var bb = new Blob([code], {type : 'text/javascript'});
    code = URL.createObjectURL(bb);
    for (var i = 0; i < 8; i += 1) new Worker(code);