I am currently running a pilot study in the surgery I work in with the 10k a Day Peeometer pack. Our local health service is evaluating the usefulness of the pedometers and I am one of the lucky few who got picked to run part of the study.
I love the idea because it is so simple - try the webiste
It gives some nice basic info. Searching Google for "pedometer steps day" will also get you some nice info (and some awful selling stuff too so beware).
Good luck with it, I hope it suits you and you get fitter and thinner (or leaner)!