Humans create the web, but we've largely abdicated the act of organizing web content to software. That could change.
Twitter this week made its new Lists feature broadly available. As they've been described, Lists, allow you to enumerate a collection of some of the Twitter accounts that you follow, and then easily read updates from just those accounts. Others can view your lists, and choose to subscribe to them as well. But Lists are also available for other applications to use, modify and share. Looked at from a slightly different perspective, this means Lists are a way to tag an arbitrary set of realtime web feeds. You could look at the lists that I've been added to as a set of tags describing my Twitter feed.
Much of the precedent for the idea of sharing (non-realtime) feeds comes from the world of outlining, and in particular Dave Winer's work here in creating OPML. Though it was designed to generically exchange outlines, OPML is the most popular format today for sharing arbitrary lists of feeds. (The computer science folks balk at some of the technical a