Discovery is a pretty broad activity for one tool, but the idea is simple. Some cycles are inward, convergent paths, meaning you end up getting deeper and narrower into a topic over time. For certain topics, this isn’t always bad. Often you would go deeper on subjects that matter to you. In general though, you want to slowly move outwards. It’s a form of diversification. You don’t want your sources to stagnate, or you could end up missing out on a larger context. The path you want to be on is the divergent one, the outward spiral. Cast a wide net first, and then edit out what’s not worth it. Unfortunately, discovery is woefully under served as a category in feed readers.
You could look at how a service like Facebook does it. Facebook uses a black box algorithm to populate your newsfeed with stories it thinks you will find interesting. It uses some form of machine learning to figure out what you want to see. It works pretty well, but most likely it is convergent, meaning it won’t budge at all from what you have looked at previously. Not the end of the world, but it’s rarely if ever going to surprise you. Part of making sure that your feed won’t stagnate is making sure that you keep pushing outwards looking for more voices.
So, if we had a discovery tool for feed readers, it should help with a few common cases: following sources, people, and possibly tags. The first two sources and people are easier to do now. Often sources will have firehose feeds for everything they publish, and if you really enjoy that source, it’s a good idea to subscribe. I really like The Awl, so I subscribe to a feed that has all their stories, regardless of who wrote them. On the other hand, I don’t always want to read all the stories that come from Wired, but I do want to know what Mat Honan is writing about. In that case, I will subscribe to just his author feed. In both cases, it requires a ton of manual labour to go find those feeds for individuals. It would be much more awesome if I had a tool that could aggregate stuff like this for me.
I call this tastestalking. You, for whatever reason, enjoy someone’s taste, and want to just follow what they have to say. In many cases, I found that people produce great content across many sites; Twitter, Del.icio.us, and Pinboard are just a few. If you end up following those people in many places, you can get a fuller picture of what and how they are thinking about certain topics, which in turn help inform your own thinking.
Another reason for discovery is so your feed is never empty. The best way to combat this is to follow people. Just follow anyone, seriously, anyone referenced in anything that is currently in your stream. The fact that someone you already read is choosing to mention another person is a positive signal.
You are also running up against a natural decay of feeds to which you did subscribe. People stop writing, they have major life events, their companies fold. There are a ton of reasons why feeds stop being published, so you should always be subscribing at a slightly faster rate then the old feeds are decaying.
And finally, edit. If a feed just isn’t cutting it anymore, kill it.