Portrait photos to make studies from - where to get them?

[karipaints]

My favorite source for portrait resources is actually pinterest. Every time I find something inspiring (or good for reference), I pin it to a relative board and suggestions pop up underneath the pin. About 25-50% of the time, I'll find yet another image that serves more reference or inspiration. I figure, if I'm already doing the work of searching for reference, why not have it a) displayed in a visual bookmarking service, and b) have free, mostly relevant suggestions based off each unique link/image.

Example from my general illustration resources board: http://www.pinterest.com/pin/220183869255076714/