There a good book about the whole history of MySpace: http://www.amazon.com/Stealing-MySpace-Control-Popular-Websi...
I'm just finishing reading another book called Click by Bill Tancer written around the same period. And Myspace had 3 out of the top 10 searches for brand websites (myspace, myspace.com, and www.myspace.com). Facebook had just appeared on the scene and was in the 10th search spot.