Check out Singaporean Wilmer Tay. He can really sketch out people (especially those Korean pop stars) with ball point pen and pencil. I know you may think there are many talented people out there who knows how to sketch. However, I have to say that his sketching is very naturally and photo-like.
I think if you look closely, you can see some tracing done before he started. He admit that this is to get the proportion right and save this time. He mentions he is not an artist by training and this is his hobby. I think if I can get half of what he can do, I will be super happy. BTW, he took 7 hours for this picture.
Check out the time-lapse video of him drawing of IU (Lee Ji-eun)