James Elkins teaches at Art History, Theory, and criticism at the Art Institute of Chicago. "His writing focuses on the history and theory of images in art, science, and nature. Some of his books are exclusively on fine art (What Painting Is, Why Are Our Pictures Puzzles?)."
You can browse for hours on Tate Papers, the Tate Gallery's online research journal. The journal is a fantastic resource for art historical and critical writing about art including many articles about painting and painters.
Edited by artist Brett Baker, Painters' Table highlights writing from the painting blogosphere as it is published and serves as a platform for exploring blogs that focus primarily on the subject of painting.