Prismatic wants to build a social network around all of your interests 13 years ago
What I find interesting about this idea is the way it crystalizes networks of interest. I think Twitter creates these networks informally, at least the way I use it, but having something more explicit offers new possibilities.
I have to add that most companies would have rested on their laurels with great UIs like the previous Prismatic apps. So, I applaud these guys for not settling on an already great tool, but taking risks to move forward.