Hi Bard, organic character modeling like faces is usually done using sub-d modeling techniques rather than with NURBS modeling. So you'll find a lot more tutorials for doing that kind of shape using polygon modeling techniques. You may be able to find some for NURBS that were done kind of before sub-d modeling became the primary way to do it, here's one that I remember from a long time ago: http://3drender.com/jbirn/ea/HeadModel.html

For already existing models, there are probably other ones on grabcad.com too in addition to the one above, look at some of these links in this previous post:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4412.2

- Michael