Internal Cross-Linking of Keywords (a la Wikipedia) for SEO

Have you ever noticed how every article on Wikipedia is full of links to other wikipedia articles? For example, the first sentence of the article on SEO reads (including links):

"...is the process of improving the volume or quality of traffic to a web site from search engines via 'natural' or un-paid..."

Linking internally serves two main purposes -- First, it allows readers to easily access other reference information that is pertinent to the article they're reading rather than having to lookup that information themselves (and possibly leading to a loss of that reader to another site). Second, it helps a lot with SEO by providing the target articles (in this case the article on "web site" and the one on "search engines") with both relevance and authority.

Relevance is given by the association of that anchor text (the underlined and linked text, like "web site" above) to that page. It tells the search engine that the page that link is pointing to is about the keywords that are pointing to it. Authority is given by the link authority that is transferred from the current article to the linked to article. Of course all the articles are inter-linking throughout the site, so the authority is being spread throughout.

The example of Wikipedia is a powerful example of internal cross-linking in effect. Think about how you can do this on your web site in a programmatic fashion that both adds value to the user (allowing them to access related content quickly - thus keeping them around for more pageviews) as well as improves your own SEO.