Next month a new book on character design will hit the stands here in the U.S. It's is called "Creating Characters with Personality" by Tom Bancroft. I got a chance to peruse a pre-release copy (it's who you know, baby) and I really liked what I saw.
Tom is a former Disney animator and a good friend of mine (check out his blog: http://tombancroft.blogspot.com).
Tom does a great job of breaking down the elements of good character design. And what I really like about his book is that it isn't merely a "How to draw like me" book. He teaches principles that anybody can put to use in their own style.
Not only did he ask Rob Corley to write a chapter (his business partner and also a good friend of mine - http://robsquirrely.blogspot.com), but he asked several guest artists to submit their interpretations of the same character. Among the guests are Peter deSeve, Mark Henn, Bill Amend and Jack Davis... yes, the Jack Davis. A very diverse collection of styles, yet with one thing in common: they create excellent designs brimming with personality and attitude.
Tom's point in the book is that good character design, regardless of style, comes down to clarity, appeal and knowing your character inside and out.
Keep an eye out for it at your local bookstore or your favorite online retailer.
P.S. Tom didn't ask me to plug his book... honest.