In general I like the idea of the Open Directory Project (dmoz), a community-edited directory of the web. The part I feel most important about is of course its KDE category. In the past I submitted several times new URLs and reported broken/changed URL and duplicates. But not so often anymore and that's not only because of the lack of time (in main parts due to countless other KDE-related stuff I'm doing): I didn't experience the category editor as very responsive. His decision to also add single pages of listed sites leads to a mess and those are the ones who are likely very soon outdated (anyone still interested in KOffice 1.1.1 release notes?). And for the major kde.org sites and close partners we always had the KDE Family Websites list, for applications and themes related stuff now kde-apps.org and kde-look.org exist and several other stuff like Reviews and Screenshots can be found linked in the KDE Wiki.
After having that said I want to add that I'm convinced that it's even so important to have a complete well-maintained dmoz KDE category. dmoz's data is used by sites like Google Directory, AOL, Alexa and over 300 others. And I'm convinced that the directory is also considered by those who offer a web search when calculating site rankings. Now my call to action: If you don't know how you can help KDE otherwise, consider bombarding the Open Directory with new submissions, update/removal requests in a single outburst or on a regular base! 
Outdated links
Would it help to create a PHP page that creates a redirect page from a database that in turn forwards the person that clicks on the link to an updated version or a correct page?
Re: Outdated links
How would you make the entries of dmoz point to that page/site? Why not ask to remove them if they are obsolete?
Obsolete
Put the proper URL in the box that points to the redirection generator? That makes it possible to move stuff around without breaking the link. Hmmm. We would need a front-end to find out the name of the referring URL...
Re: Obsolete
I guess you don't understand that this isn't about moved pages within kde.org domains: kde.org uses a 404 handler and redirection.