Here's some code to easily generate RSS feeds from ASP.NET. It only generates RSS 2.0 feeds at the moment, I may update it to generate other types of feed at some point. To use, add a WebForm to your project and change the code so it inherits from RSSGenerator, rather than Page. Then remove the auto-generated HTML code added to the page. To add items to the RSS feed call the AddItem method from the Load event or override the PopulateFeed method.
Here's the class and here's a RSS feed for the computer's event log.