You've seen many ways of creating RSS feeds so far. But what if you don't want to create an RSS feed, and instead you want to gather information from existing feeds? With thousands of feeds on the Web, there's no reason you need to create your own. Why not put together several feeds on a topic that interests you?
In fact, you can make those RSS feeds available to people who don't usually read RSS, by converting those feeds to RSS format.
When you start republishing other people's feeds, you might need to get permission first. At the very least, make sure you cite the sources of your information.