Java applets are an old technology that no longer serve a legitimate purpose. It's too insecure, too dangerous, too clunky, doesn't work on mobile, and you may have to deal with Oracle's malicious Java updater.
Client-side Java is dead. So, honestly, if your browser is secure, none of the following should work for you. HTML5, WebGL, and other modern technologies, as seen above, are a far superior option. These demos are left here for historical purposes only.