James Gurney is the mega-successful illustrator creator of the Dinotopia books.
His blog is mostly instructional in nature, somewhat informative, kind of off-the-wall and often updated.
I read this post today about how to draw apes from life and the solution he came up with was just brilliant:
The gorilla loved it. He had never seen a human act like a polite ape before. He came right up to the glass and posed for me while I did this half-hour portrait from just two feet away.
click here to see the whole article.