I recently discovered Sktchy, an app that joins artists with people sharing their photos (most of them are artists too). It was love at first time. Free, easy access to really good reference photos of people from all over the world. Sharing with other artists, all of us trying to do the same thing, capture the face with some kind of media.
Here is a small selection of the portraits I painted with a brush pen. A brush pen is actually a tiny paintbrush which is fed ink like a fountainpen.