Best way to mark or filter articles based on content?

[icewater]

I'd like to do a couple of things based on article content:

• Filter articles based on content. If the article contains a term I would like to not see it in the article list. Ideally it would stay in the database so I can search for it at some future date.
• Add a visual indicator to articles based content. For example, I have several news feeds that otherwise have value but are biased on certain topics. It would be useful to set a match rule and an indicator for that rule (specify an icon to show next to article, or change the color of the title text to yellow :-) ).

I don't know if this is something I can do with an external tool, or technique, or if I should submit a feature request.
Thanks!