Keyword to URL allows admins to create and save a list of keywords paired with URLs. Any keyword appearing in a post is then shown as a link.
The plugin allows administrators to build and save a table of keywords and URLs. Once saved any post (or page) that has the keyword will now show that word (or phrase) as a link.
You can choose to link every occurrence of the keyword in a post or just the first occurrence.
The plugin also recognizes email addresses as links.
Anytime a keyword is already linked in a post it will be left unaffected by the plugin (that is, you can override the plugin's links by just adding your own anytime).
You can signal a post to not use the plugin's linking by adding a comment anywhere in the post: <!-- no keywords -->
See the plugin's project page for more usage tips.