OK, forget XFN. Now what?

In Many-to-Many: XFN Relationships Clay Shirky convinces me that XFN is wack. But can we just pick a model and let people experiment with it? I don’t care if it’s FOAF or XFN or PeopleAggritude or whatever.
What’s the best way to build out and model the part of my network I want to be partly exposed online?
Extra credit question: What was it that was originally proposed as the “simplest database that could possibly work”?