I love portraits. There is just something about faces, the shapes and sizes of the eyes, mouths and noses, foreheads and chins. All that combined with scars, wrinkles, lazy eyes and other small imperfections that everyone has gives one a large palette of drawing reference. Also, the feeling you get when someone actually recognizes who the person you drew actually is, now that's pretty awesome ;)
So, portraits of various people, mostly the ones I can find good reference of :)
A Darth Vader self portrait? Heh, I really like Star Wars...
The amazing Ian Anderson