Justsketchme allows me to pose characters quickly and intuitively. This provides me with customised perspective references for drawing with the appropriate forshortening of body parts as necessary. No more manual manipulation of wood manikins or little plastic character kits!
There are some built in poses to select from as well as lighting options to help me appreciate where shadows would be cast. I then take the posed image into my drawing application and use it as a reference for developing my own characters.