Since I'm back on my way to beating my current physical plateau, I'm doing my best to become accountable to myself for my progress, as well as to others. A while back, I found Spark People, which is a fantastic resource for diet, nutrition and exercise. I've set up a profile, which allows me to keep track of the exercise I do, as well as the health value of what I do and what I eat. There are community aspects, as well as a boatload of information, in addition to fitness and nutrition plans that you can use if you wish.
It's been a great resource, especially because I still receive e-mails with suggestions for exercises and recipes that I check out, even when I've been slacking as an active participant on the site.