I have a fitbit and I absolutely love it.
I also bought the aria, the scale by the same company.
So I'm basically tracking myself 24/7
I've found the little sleep tracker wristband thing that comes along with it useful. Before you go to bed you stick the fitbit in the wristband. It tracks your slight movements I think, and records how long you were in bed versus when you were restless. Since lack of sleep makes people eat more, it was helpful to motivate me to get my "quality sleep" up to 8 hours by getting to bed earlier. You can also plug it in to a sleep debt site which will take your fitbit sleep data and give you guidelines about how to pay down the sleep debt you've accumulated.
The aria is great too. I wake up in the morning, step on the scale, and it automatically transmits my weight and body fat % (body fat apparently found via a harmless current) using my wireless to the my fitbit stats. Couldn't be easier. So cool to see my chart of weight/bmi/bodyfat going down on their site.
Then I just clip the fitbit on my pant waistband (agree with meltitaway it's very discreet) and it keeps track of my steps and stairs climbed during the day. The best part is the motivation to keep moving. For instance, today I made sure to walk enough to reach my minimum goal of 10k steps, and then I noticed when I looked at my stats that I would reach a badge/milestone if I reached 70 floors climbed and I was almost there. So I stopped on my way home at the park and walked up some stairs a few times. Yeah, it's sort of silly motivation (they send you a cute email when you reach a goal or achievement, and your stats on their site show your past glories
), but it works to keep you going, if you're already somewhat motivated.
There's lots of other cool features, but those are the highlights for me.
If there was one downside for me it would be that the fitbit needs to sync with this little usb plugin thingy in order to update your daily stats to their website. It's not a big deal, when I come home and turn the computer on it automatically syncs up since my fitbit is in the 15 ft. range of the device. But it would be nice if there was some way I could see my stats update in realtime on the ipad or iphone without being near my computer. You can of course read your steps, stairs climbed, calories burned, etc.. on the small display on the fitbit itself.