I've got Taschen's '1,000 Nudes' fat collection of vintage nudie shots, disclaimer: it does contain an early chapter of Victorian-era porn, so keep it on your top shelf, if you've kids running amuck.
Otherwise, I find the more fine-arty photos to be of use, especially the sort of 'mythological' themed ones where naked ladies are running around with bow and arrow, and men are stacked in gymnastical contortions like a circus act. Advanced figure drawing material!
I have some other favorite reference books I'll share in the future. My favorite live model session is on pause until January, and now some nights are getting to be too cold to leave the house, so I'm looking to get creative about practicing.