Choosing Content for RSS Feeds:

Any list-oriented information on your site that your viewers might be interested in tracking or reusing is a good candidate for an RSS feed. This can encompass news headlines and press releases, job listings, conference calendars and rankings (like 'top 10' lists).

For example:

News & Announcements - headlines, notices and any list of announcements that are added to over time 
Document listings - lists of added or changed pages, so that people don't need to constantly check for different content 
Bookmarks and other external links - while most people use RSS for sharing links from their own sites, it's a natural fit for sharing lists of external links 

Calendars - listings of past or upcoming events, deadlines or holidays 

Mailing lists - to compliment a Web-based archive of public or private e-mail lists 

Search results - to let people track changing or new results to their searches 

Databases - job listings, software releases, etc. 

While it's a good start to have a 'master feed' for your site that lists recent news and events, don't stop there. Generally, each area of your site that features a changing list of information should have a corresponding feed; this allows viewers to precisely target their interests.

For example, if your news site has pages for World news, national news, local news, business, sports, etc., there should be a feed for each of these sections.

If your site offers a personalized view of data (e.g., people can choose categories of information that will show up on their home page), offer this as a feed, so that the viewers' Web pages match the content of their feeds.

A great example of this is Apple's iTunes Music Store RSS feed generator; you can customize it based on your preferences, and the views it allows match those provided in the Music Store itself. 

Finally, remember that feeds are just as - if not more - useful on an Intranet as they are on the Internet. RSS can be a powerful tool for sharing and integrating information inside a company.

What is XML? 
Syndication Options
RSS Resources & Downloads