Recently Brent Simmons talked about marking all items as read in your feed reader. This is a solution to falling behind and having too many unread items. For me, as a user, the problem with this strategy is that there are certain feeds that I never want to miss. For example, there are developer blogs that only post items a few times a year. Do you want to go on vacation for a week, fall behind on reading your subscribed feeds, and then miss one of those rare posts because you had to declare "unread bankruptcy" and mark all as read? More important, there are feeds that I use for work. We have a feed of commits to the repository, and I never want to just ignore those.
As a (former) developer of a feed reader, the solution seems obvious to me. You should be able to mark certain feeds as "important". Then either the "mark all as read" command would skip those feeds, or there could be an additional command "mark all unimportant feeds as read".
The objection of course would be, if a feed is not important, then why are you subscribed to it at all? Perhaps "important" and "unimportant" are not quite the right words. "Mandatory" and "optional"? "Professional" and "recreational"? Whatever you call them, I think you can understand the idea. It sounds odd to me to suggest that you shouldn't subscribe to a feed if a few times a year you lack the time to read it. If you're busy one day, and you don't read the news, does that mean you should never read the news?
I'm old enough to remember back when people (including me) subscribed to newspapers. Newspapers made of real, physical paper, that got delivered to your doorstep every morning. If you went out of town, you would come home to a pile of newspapers. Would you go back and read the whole pile? Perhaps, but probably not. The important thing, though, is that you wouldn't cancel your subscription to the newspaper just because you had to go out of town once in a while. That would be silly. (Actually, it is a good idea to temporarily suspend your subscription so that thieves don't notice the newspaper pile and target your home for theft.)
People also claim that if something is important enough, you'll see it on Twitter. Well, having been on Twitter before myself, I think I can safely say that nothing important ever happens on Twitter.
P.S. The reason I deleted my Twitter account was that they stopped providing RSS feeds.
P.P.S. I've applied for a patent on the method and apparatus of marking only unimportant feeds as read, so if you implement my idea in your feed reader, you have to SHOW ME THE MONEY.