Suggestions for an Ergonomic Mouse?

pawul13 asks: "I've seen lots of articles and suggestions on ergonomic keyboards (and I have the excellent kinesis version, which helps tremendously), but what about mice? I'm currently experiencing a lot of pain, but only in my 'mouse' wrist. I have a semi-ergo Logitech, but it's not doing it. Does anyone have suggestions for the best ergo mouse (Trackball, optical, whatever, it doesn't matter)?" There was a similar question from January, but it may have been too limited.