For me, Facebook means privacy. I can edit whatever I want to, put up content and still get to choose who sees it and much more. As compared to Orkut, Fb is definitely more interactive. It's much more than just networking. So I suppose it;s become popular amongst youth living in metros...
Astrology to some extent is based on scientific principles and careful mathematical calculations. So some of the estimations( I wont use the word prediction per se) do come true. I wont say that Im a manic believer and that my day wont start before I get to know what planets are in what houses...