Unfortunately, however, it doesn't seem to be available for Mac. You can create virtual models, change their proportions, resize them, give them insane muscles or slender hips, and in general it's truly a flexible and useful tool. DesignDoll is a tool I've been using to improve my anatomical skills since June, and while I'm still far from the best I've noticed many improvements in my figures.
I'm rather surprised this program hasn't been mentioned in the sub yet.