This website was shown to me by a friend and its pretty sweet for those of us who find it hard to get out to life drawing sessions.
It helps simulate a normal drawing life drawing session by cycling through these 3D models in different poses. You can do 10 sec, 30 sec etc poses. My only issue with it is that the models don't have "skin", there are no overweight models and the breasts on the females don't stretch according to how the arms are raised. But for just needing to get warmed up, not a bad deal.
Nothing beats a live model though.