In relationship to SEO, the bottom line is you may disseminate your web sites articles, news, and web pages to other third party sites. When a reader finds a headline of interest it brings them to your site for the full article.
I have one of my favorite links directories SEO: RSS Feed Directories is currently available to non-registered users. Once I'm convinced I've submitted my own sites to all the directories I've researched with any page rank value or real tangible value to my mind, I'll close my favorite links category SEO: RSS Feed Directories to registered users only... Needless to say, there are several of my favorite links categories that are only available to registered users ;)