I was playing around with ranking your contacts by mood. 

The idea behind this is being able to sort your feed by how someone's notes make you feel. The user assigns internal rankings to each person they interact with. The rankings are just mood indicators:

1. Informative - high signal.
2. Positive - I generally feel good about the notes from this person
3. Neutral - I'm in different to what they say, they tend to post neutral content that does not influence me emotionally. 
4. Negative - this person makes me feel crappy sometimes or often, but I follow them because they occasionally say things I value or find interesting / makes me think.

Then you could rank your feed based on how you would like to feel. If you wish to over time feel more positive, you could select only to show positive npub notes. That doesn't guarantee that everything you see is going to be happy, but it should TREND the mood towards positive. 

Or if you wish to see only informative high signal content, perhaps you set your feed to that and only see high signal notes. Again, you will see other types of notes there, but it will trend towards highest signal. 

This could also be expanded to other types of indicators such as "responds often" for example, so you can interact with people who actually respond.

The benefit over just a followed set of people is being able to toggle signal for the day, or relaxing your criteria to include everyone.

UX: you have a hold+drag slider that selects the mood for that user. This is only visible to you (unless you share a screenshot lol). This makes it easy to categorize npubs (assuming you don't misclick into their profile) - to be tested.

Right now this is just an exploration and an idea. I'm putting it out there to see what people think of it. 

Originally I was thinking about this from the WoT perspective, but then realized that probably wouldn't work. 
https://void.cat/d/R6gqKzKNb4nf69XhtEpvPd.webp