Nike introduced the Nike+ SportBand this week. It's a little USB device that stows away on a wrist strap and records the data from your Nike shoes. Later you plug it into your computer to upload stats to Nike. It includes the in-shoe transponder and it's only sixty bucks. Don't have Nikes? Ziptie the transponder to your existing shoes and use "calibration" mode to teach it how they "feel."
Some marketing genius got their wings for the up-sell possibilities, but I can't wait to see what the alternate reality gaming people think up!
Suppose you want to walk X miles per week as part of your commute ... but you never know when the bus will appear *while* you're walking to the next stop, making you wait for the next-next bus.
Now I'll bet your phone has rudimentary GPS and *some* internet capability. So you punch up www.mightaswellwalk.com and it looks up the next bus' arrival time, distance to the next stop, divides by your average morning/afternoon pace and tells you "might as well walk!" (And if you're whey under your weekly goal it could nag you, "better walk!")
This could get really interesting!