Mostly women
http://senshistock.deviantart.com/gallery/
http://ladystock-archives.deviantart.com/gallery/
Men
http://manstock.deviantart.com/gallery/
http://daestock.deviantart.com/gallery/
backs
http://backward-perspective.deviantart.com/gallery/
Action Poses, both sexes
http://action-stock.deviantart.com/gallery/
http://daposes.deviantart.com/