Syndicate Press lets you include RSS, RDF or Atom feeds directly in your WordPress posts, pages, widgets or theme.
It simply works. The problem is it is too simple.
Feeds are separated, which means that this plugin shows posts from feed A, then posts from feed B, and so on.
Easy to configure and it works. There may be "fancier" plugins with more options, but if you need one that works reliably, this is the one.