Often I find myself trying to rediscover why I followed someone on Twitter or Tumblr. Did they post something original & interesting? Did I follow them because I was curious about what they were up to? Several weeks or months after the decision to follow, I have no easy record of why I made that choice.
Facebook has a “friendship details” option, which is interesting, but fails in practice. Since it requires both parties to agree to the type of relationship, the social friction prevents all but the mutually-neurotic from providing meaningful info. Further, it doesn’t permit private relationship details.
So here’s the feature request: I’d like the ability to privately text-annotate my following/friending activity in each of these services. This would allow me recall the value I saw in the relationship when I formed it. That’s a win for me, and for the services that succeed when they create valuable connections.