Quite often, people wonder what the value of a link on a page is - not in terms of dollar value - but in terms of how much benefit to your site a link on a page will pass to you. Various factors such as number of links on the page, relevancy of the topic, and PR all affect this value. A good tool to use to help make these judgements can be found at http://www.123promotion.co.uk/link/index.php.