This website,
My Calorie Counter, seems to offer a lot of tools in this area.
I currently only use it to track my weight and bodyfat %. I'm not too much of a calorie counter, so I just watch what I eat and try to focus on more fruits/veggies.
But, it does track weight loss, there is a public webpage/blog section, and you can form communities with others.
Why reinvent the wheel? (Of course, I'm sure there are many more websites that do something similar.)