The best I've read is probably "Chaplin: His Life and Art" by David Robinson, which is a biography unfortunatly, but its still the best thing on the filmmaker to date. There's really not much I can bring to mind as far as analysis is concerned, but there's also "Chaplin: Genius of the Cinema" by Jeffery Vance, which has some interesting stuff. There was one book (I think it's called "The Art of Charlie Chaplin") which is mostly analysis of Chaplin's work, but it's one I find myself often disagreeing with, and it's dismissal of post-dictator Chaplin is simply a crime.
Oy! And there's also "My Life in Pictures" by Chaplin, which is mostly just photo's of Chaplin at work throughout the years, but it has some great antecotes by the man himself on his work.
Chaplin's My Autobiography is great reading too, though it often strays from Chaplin's work life. He says Monsieur Verdoux is his best film in it though!