Most people who used the Google Toolbar probably never went through the effort of enabling the PageRank meter, which Google offered as an incentive to web surfers, a way for them to understand the quality of pages encountered when browsing (and a way for Google to understand what people were viewing beyond Google itself). But one group was very inclined to make the effort: SEOs.
Google will index this link and see that ESPN has a high authority, and there is a lot of trust in that website, but the relevancy is fairly low. After all, you are a local plumber and they are the biggest sports news website in the world. Once it has indexed your website, it can see that they do not have a lot in common. Now, Google will definitely give you credit for the link, but there is no telling how much.
One final note is that if the links are not directly related to the subject, or you have no control over them, such as commentors’ website links, maybe you should consider putting them on another page, which links to your main content. That way you don’t leak page rank, and still gain hits from search results from the content of the comments. I may be missing something but this seems to mean that you can have your cake and eat it, and I don’t even think it is gaming the system or against the spirit of it. You might even gain a small sprinkling of page rank if the comment page accumulates any of it’s own.
Steve, sometimes good information to users is a consolidation of very high quality links. We have over 3000 links to small business sites within the SBA as well as links to the Harvard and Yale library, academic journals, etc. But because we have the understanding that there should be no more than a hundred links in a website (more now from what Matt said) we have used nofollow on all of them out of fear that Google will penalize our site because of the amount of links.
Make it as easy as possible for users to go from general content to the more specific content they want on your site. Add navigation pages when it makes sense and effectively work these into your internal link structure. Make sure all of the pages on your site are reachable through links, and that they don't require an internal "search" functionality to be found. Link to related pages, where appropriate, to allow users to discover similar content. Denver Page Rank Click Here