You would have to define what flat was....no
rotation curve on any galaxy is completely flat. Just a quick sample of a few galaxy rotation curves will see that this is not the case. They're not entirely flat to begin with, even if the average velocity of the rotation curve produces a relatively flat line outside of the nuclear regions. The flat line is a "typical" idealised rotation curve. Most spiral galaxies do follow it to a degree. But then again you have to remember that universe is made up of more than just spiral galaxies. However, most galaxies do not show a Keplerian rotation curve and the rotational velocities do not drop off in accordance with Kepler's 3rd Law. That means there must be either more mass outside of the orbit of the Sun (in the case of our galaxy) or the spiral arms of the other galaxies...and/or...gravity isn't working in they way we'd normally predict and has to be modified to account for the rotation curves seen.
As for the social networks, I think they're a good idea but facebook isn't the way to go. Not for this type of discussion and not in that sort of forum. They would be hounded by all sorts of crackpots and nutters and nothing fruitful would come of the network.