Javascript in-browser editor with CTRL+SHIFT+Y shortcut to execute the content. Just put it in your address bar and press enter. It works only on Chrome.

Ruby Notepad Bookmarklet

data:text/html, <style type="text/css">#e{position:absolute;top:0;right:0;bottom:0;left:0;}</style><div id="e"></div><script src="http://d1n0x3qji82z53.cloudfront.net/src-min-noconflict/ace.js" type="text/javascript" charset="utf-8"></script><script>var e=ace.edit("e");e.setTheme("ace/theme/monokai");e.getSession().setMode("ace/mode/javascript");addEventListener('keydown',function(evt){if(evt.ctrlKey && evt.shiftKey && evt.keyCode==89) eval(e.getSession().getValue());});</script>