Fitbit and it's just about the neatest thing since sliced bread and peanut butter. This thing works great without all the problems associated with Bodymedia and their non-existent customer service.
The Fitbit is about the size of your pinkie which clips to your belt, pants, shirt, or you can just put it in your pocket. Through the day it measures how many steps you take, your mileage, whether you are just strolling or running, and it even has an altimeter function that can track how many flights of stairs you climb. You can check the stats on the Fitbit any time by pressing a little button. Another cool function is that you can take it to bed and track your sleep pattern ....documenting how long it took you to fall asleep and how many times you briefly wake up during the night.
The Fitbit downloads to a website every time you pass within 15 feet of the little docking station that also acts as a re-charger. On the website you can compile all the data as well as add other things like foods you have eaten, weight, and even what type of mood you are having on any particular day. Oh...and the website is free. Buying the Fitbit is all you need, no monthly membership required. They do have a premium website that gives the data in a lot more detail for about four bucks a month. I may get it someday but it's truly not necessary to get the stats you need and want.
I love this thing. I even bought one for my wife who is not all that into fitness tracking and she loves it too. It's not cheap. It runs about a hundred dollars but if you're serious about keeping track of all your stats, don't want to spend all your time writing stuff down in journals, and want something that gives instant feedback on your efforts....I highly, highly recommend this product.