sage, a firefox plugin, vs. NetNewsWire, a beautiful cocoa app (free/shareware). Fortunately, each can read the other's OPML file.
Once musicmobs has sucked in my iTunes Music Library, I can enjoy Mobster's telling me what to listen to (on a sliding scale of "Hipster" to "Mainstream", where, presumably, the former entails Decembrists and The Faint, the latter Coldplay and Interpol).