While perusing Adam Sampson's website (the author of rawdog), I noticed that he maintains a list of ideas he's had. I think that's a great idea, so I'm going to take note of something that occurred to me a few moments ago.
I often glance at Planet Gnome (PGO). I'm already subscribed to many of its syndicated authors, but every so often someone who hasn't posted in a while shows up on its front page, and I find someone new to subscribe to. But therein lies the problem: I'm wasting significant time maintaining a separate list of feeds. PGO has a blogroll in two formats, but my current feed reader doesn't give me any tools for filtering out the authors and content that are irrelevant to me.
Linus Torvalds once noted that "If you can do something really fast, really well, people start using it differently" (skip to 50:38). He was talking about merging in git, but I think it applies to feed reading as well.
Earlier this week I found an author who was posting about a bit of software he had written. I was discouraged from subscribing to his blog because he used tags and categories so disjointedly that I knew that by subscribing to a tag- or category-specific feed I would either be inundated with unrelated posts, or I would miss relevant content that I really wanted to see. And that's when it hit me (again) that my feed reader doesn't (and all feed readers I've ever used don't) give me the tools to insta-subscribe, and insta-filter, and insta-unubscribe (heaven forbid) when it's clear that the content doesn't interest me any longer.
If and when I write my own feed reader, I hope I remember to make it incredibly easy to subscribe to feeds, but brain-dead easy to filter content on my terms.