I really like the Fitbit. It is totally plug-and-play. It uses sensors similar to a Wii
remote to track steps, stairs, and overall activity level. So it will detect the
difference in effort between walking and running, for example.
You clip it on (on a belt loop or pocket, or use the special clip-on holder for it)
and you plug in a little USB access point to your computer. Every time you go
near computer it uploads your data automatically.
It also comes with a fabric sleeve you can wear at night, to hold the fitbit to
track how well you sleep if you like.
Anytime you want to know your stats, you just log in to your account on the
Fitbit site and look at the graphs and numbers. You can also enter data by
hand, such as calories consumed, but I haven't bothered to do that. (I also
have
not enabled it to share my data with any social networking sites!)
I can look at my activity level graph for an autocross day, and figure out when
I was walking the course, chasing cones, or just sitting on the sidelines.
I also have a Withings wifi scale, which I've linked to my Fitbit account.
(YMMV of course... but I've lost 10 pounds in the past year.

Amazing
what a little graphical motivation can do.)
http://www.fitbit.com/http://www.amazon.com/Fitbit-Wireless-Activity-Sleep-Tracker/dp/B005PUONIK/This is the newer model, which tracks stairs as well as horizontal steps.