I've shared my experience of using PoseIt before, but I just can't stop enjoy it. It helped me with some of my recent artworks, as you can see :) I used to have a lot of troubles building anatomically correct bodies (and hands, omg!), I can't say that my anatomy skills are perfect now, but they seem to become much better! :D
If there are artists in my little community, I highly recommend to use this app.
P.S. If you think I was paid for this advertising, unfortunately I wasn't :D, just want to share a good tool for artists I use myself)