200 hours for first Skyrim playthrough on X360.
Another 150 hours for my second playthrough.
Then about 60 hours on PC.
So yea, roughly 410 hours on Skyrim. And I'll probably go back and play it a bit more at some point.
At some point, Assetto Corsa will probably overtake it, though. At 278 hours and I'm pretty sure I'll still be playing it for a few years at least.
I've never played an MMO and when I see people posting 1000+ hours on them, it really scares me off doing so in the future. I remember I basically lost a friend to Ultima Online back in the day. Once he started, it became all he ever did.