Automatic link generator based on keyword


I have an site similar to a wiki, where there is a lot of content
displayed per page. I was wondering if there was a plugin that would
automatically add link_to tags on keywords that I specified and link
them to the pages that I specify. For example the plugin I would
identify the keywords and links first;

keyword = “Printer zxy”
link = /product/printer-zxy

and then it would automatically fill in all the proper links if that
keyword is displayed in a specified area, like the product
description. I have searched but have not found anything. If anyone
has come across a rails plugin that automatically generates links
based on keywords I would greatly appreciate if you shared it. If not
I might just have to write something up. Thanks in advance.