I don't know if anyone else has looked at Yahoo PIPES, but boy can you ever create amazingly unique RSS feeds.

Takes a bit of a developer mindset though.

Here's a page where you can type in your keyword or keyword phrase and grab a unique RSS feed.

http://pipes.yahoo.com/prmpipes/contentkeyword

I'm going to dig into PIPES to create a few feeds and will let people know how easy/tough it is.

Good luck.

Ernie