You often hear about how different Facebook and MySpace’s user bases are. Well, maybe they’re not so distinct after all. Yahoo is the No. 1 traffic referrer to both sites. (Hat tip to the purple team). What’s more interesting is how much traffic they actually send to each other: Facebook is the second-highest traffic source to MySpace, and MySpace is the third-highest traffic driver to Facebook. The other sites they get the most traffic from are portals (guess portals aren’t exactly “dead”) like *AOL*, MSN and, of course, *Google*. As for the app developers, it’s worth noting that Zynga and RockYou are two of the top sources of traffic to both nets.