Yes, I agree, lists. Hashtags are important. Maybe in the future, groups too. A client with a heavy leaning on lists would be good. I like primal a lot, but their trending data is somewhat worthless in the scenario I'm thinking of
Discussion
Has an interesting take on this, with feed primarily curated by followed hashtags, and allowing reddit style up/down zaps. You can set it so down zaps go wherever you choose. So a charity or a friend maybe.
Yes I had a look at that, looks cool