As I detailed in my life-tracking comparison feature and in other posts, the Fitbit is an excellent device for tracking all aspects of your daily life, including the steps you take, how many floors you climb, how well you sleep, and how well you eat. It is available for $99.95 and I don't go anywhere without it in a pocket or attached to me.
Fitbit also launched an Android Food Plan app that helps you log your daily food intake so that you can set and achieve your eating goals too.