This is a bit of code I whipped up for Talk Like A Pirate Day 2006. It converts the text on the current page to pirate lingo.
To use it, download tlapd.js and install it someplace on your web site. To convert a page to pirate, add a line similar to the following inside the <head> section of the page:
<script type="text/javascript" src="/path/to/tlapd.js"></script>
If your site uses a standard header template, put it there.
This code is distributable under the terms of the GNU Public License.