It seems to me that every pitch for a social networking site is just as good (or bad) as the next. At the moment, the only clear difference between the sites is

It seems to me that every pitch for a social networking site is just as good (or bad) as the next. At the moment, the only clear difference between the sites is whether it has caught on in a big way or not. The network effects in play pretty much drown out all of the other, seemingly important details like theoretical audience size, technical goodness, aesthetic design, and charisma of the founder.