RSS Subject Collections - FeedRinse can help!
There are lots of great mixers out there (see RSSMix, as an example) that will allow you to splice together mulitiple feeds, but other than FeedDigest, none do a great job of filtering those feed collections down for concepts or subjects.
If we're going to put together RSS Subject Collections, we need to be able to mix together multiple quality sources on a subject, then filter things down to a conceptual level. If HBS Working Knowledge publishes an article on 'Global Economics', we want it in our Economics subject feed. What we don't need is all the other stuff, which is where filters like FeedRinse come in.
Librarians in the room take notice. Want to know where the future of our profession is? Mix together some traditional collection development theory with these tools to combine & filter RSS feeds -- the results are a truly dynamic product (and profession).