Nintendo's Personal Trainer: Walking uses its wacky pedometer doodad to tabulate your step count every day and send the data back to the DS. This data goes to Nintendo for use in step count leaderboards. You can compete to top the charts like in many other online games, except the competitive activity here is exercise.
Does the idea appeal to you? Do you think vying for the top spot on a leaderboard will inspire you to walk more? Or are you extra awesome at walking and looking forward to the chance to show that off with numbers?