Here's a step by step guide for getting into the news feed world.

1. First create the river for your own internal use. To support your editorial team. Ask around for links to the other reporters, news orgs, bloggers they read regularly. Then compile a list of their feeds as a flat text file with the URLs to the feeds, one per line. Here's an example.
2. Download River5 and follow the setup instructions. You already have your list file ready, put it in the lists folder then fire up River5.
3. Wait a few minutes. Have a look at the river. Add some more feeds to the list. Repeat until you have a resource that your editorial people use. It could take a week or more until the river is useful, but it will be time well spent, because you'll be exploring the world around you in new ways. Seriously, not kidding. 
4. Don't forget to include your own publication's feeds in the river. Everyone needs to know what other people in the org are writing about.
5. After a while tell your readers about the river. Solicit their feedback, then ask for feeds that they love, no guarantee you'll add them to the river, but try to.
6. At this point you'll probably get more ideas. Iterate, improve, and hopefully send me an email telling me how it's going. I love to learn about real users' experiences.