An excellent thread at SEOChat points out the defintion of RSS (Really Simple Syndication) and how it's use in websites for SEO purposes can help to boost things like pages indexed, fresh content, and the "long tail" of search visitors. In particular, several resources were pointed to:

• How to Make Your Own RSS Feed with PHP
• An Automatic RSS Generation Tool
• An Overview of RSS

In addition to SEOChat, Cre8asite also has a good RSS thread going - this one eventually focuses on the true value of updated content, and Ammon Johns points out that fresh content doesn't just give a boost for being fresh, it also generates more links, more content and thus, more chances to be found in the SERPs.