Tweetwhatyoueat
Tweetwhatyoueat is a free Twitter-based food diary. The idea is to tweet everyday your answer to the following question: "What did you have to eat today?" You can track your food intake, calories, and weight. Since it uses Twitter, you can track all of this information using any device including your mobile phone, IM, or the web. The web site has listings of the history of what you ate and your daily total. It also lists the total number of your entries, which you can compare with others who use the site.