automatic link generator based on keyword

Hello,

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.