Yes, in fact jQuery hosts a copy of itself on a CDN available with this script inclusion tag:
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
CSS files can be included in a similar fashion, instead of a relative path use the absolute path (starting with http:// typically, or the double forward slash for shorthand).
Here's a pretty awesome CDN that hosts a ton of stuff.