A short history of JMK in TNR, which nicely lays out his views as represented by the General Theory and other works.
I'm reading the Robert Skidelski biography, which does a very good job of situating JMK in the late Victorian/Edwardian era. It's interesting that economists are always creatures of their times. Cannadine's Mellon, for example, was more interesting as a view of late 19th/early 20th century economic and industrial/scientific history than it was as a biography of Andrew Mellon himself. Keynes appears to have been much more of a character than Mellon was, however, and was surrounded by similarly colorful characters.