One of the nice things about the SharePoint Content Editor Web Part is that it lets you easily include your own html and javascript without having to modify the page structure itself and that works really well for most things.  However, many third-party and hosted utilities require you to embed a script in your content that looks something like this :

   <script type="text/javascript" charset="utf-8" src="http://external.url.com/SomeID/TheirApp.js"></script>
   <noscript><a href="http://external.url.com/SomeID/">Click here to do something wonderful</a></noscript>

Simple enough and anyone can paste that in.  The catch comes when the javascript file that you are including writes its own HTML into your page. Click to read the full post