WordPress.org

You can automatically link keywords and phrases in your posts, pages or custom posts. Simply select a keywords from your tags or any other keywords you want to make links from your posts or pages.

Features include:

*Work for Custom Post Types *Process RSS feeds *Add your Custom Css *"nofollow" attribute support *Count views per key *Expiration per key *Limit links per page/post *Select keyword from your tags list.

Plugin's Official Site

WPmanage (http://wpmanage.com/Own-text-links/)