The most useful feature of the site is, however, a motivational one. Sparkpeople rewards users with "sparkpoints" when they login to the site, record the food they've eaten, exercise, read health-related articles, and many other things. If you accumulate enough points, you can move to the next level. The levels are mostly symbolic, but reaching the next level is ironically addictive.
I thought the reason was because I'm a gamer. Some part of me hopes that the next level will allow me to use better gear and give me the ability to blow crap up with my mind.
Actually, however, my wife has been more insane about sparkpoints than I have, and though she's been around gamers all her life, she has not yet imbibed the kool-aid.
I think the reason these points work so well is that people are eager to see immediate successful results, even if they're fake. It's one thing to have a far-out goal that you want to reach some day; it's another thing entirely to feel like you're steadily reaching that goal, piece by piece, day by day, point by point.
With this in mind, I'm going to do an experiment. I'm going to apply the Point Principle to every aspect of my life for a week, or as many as I can think of, and see what happens. Come back next Monday to find out how it went.