Personally my favorite pedometer pet is the Digital Monster Vital Bracelet. It's got its own app where you can battle your digimons and stuff, and it keeps track of your steps and even gives you little missions to walk so many steps or even do other exercises like squats and crunches (those are optional, of course). You can buy add-on cards to get more monsters or just work with the ones they start you with (which there are plenty of!)