The current spate of RSS feed-reading tools is missing a major feature: None of them (Bloglines, Google Reader, NetNewsWire, etc.) provide help with answering the major focus problem, "Which feeds should I pay attention to?" They are great at collection (one of the five GTD workflow phases I teach clients - gathering new feeds, and sorting them by source, date, number of unread, etc.) but that's just creating a bunch of haystacks. They still require us to laboriously look through each to find the needles (i.e., to assess value).
And this leads us to the real problem:
The links from source to value are one-way, with no feedback.
Here's an example. You're reading through your feeds, and find a post that takes you to an interesting idea (The Rule of Least Power, for example). You jot some notes, save the URL, then move on. Repeat. The problem is the feed reader doesn't know that the article did something important to you - gave you an idea, changed your perspective, made you angry, whatever.
It's like loosing the Chain of custody, or not knowing a painting's provenance. Without completing the cycle back to the source, the reader can't filter feeds by importance, leaving it to us to do manually. (For example, see Bob Walsh's 80/20 Your information feeds idea - though determining which 20% is valuable is hard - and Marshall Kirkpatrick's Open Sourcing My TechCrunch Work Flow.)
Naturally there is work going on in this area. Google has its trends feature (click here if you're a Google Reader user - found via Robert Scoble's article 25,000 items read on Google Reader), and NetNewsWire's neat Sorting by Attention addition. But without having note-taking integrated in the information stream (which suggests standards, or an OS-based solution), tools are limited to impoverished metrics (e.g., clicked-on-post, flagged-feed, sent-to-someone, bookmarked-it), and can't do a good job for us.
How would this work? I haven't thought it through (suggestions anyone?), but maybe a cooperative set of browser plug-ins, sort of a "Zotero meets PageAddict, gets married, has kids" mashup.
The bottom line is I want something that knows when an information stream - podcast, web page, blog post, email, or video - passes the scribble test.