I just discovered a really great reference for drawing human faces and wanted to share it. FaceGen Modeller is a 3D face modeling program that is fully customizeable, from all facial features to age, expression, race, and more. You can also create a model from a photo reference, and all models are viewable with a 360 degree turnaround.
The free version has almost all the features of the paid version, less some export capabilities and a logo on the forehead. As a reference tool, though, this can be extremely helpful. I've already rendered a couple of my characters, ones that I've found difficult to draw.
Hope this helps someone else like it's helped me!
