I use an app called Pacer on my phone to keep track of steps. Its a fairly nice app that doesn't eat too much of your battery. It allows you to put in height, weight and stride length, which makes it fairly accurate. It gives you an estimate of how many miles you've walked and how many calories your burnt as well. I just received an update yesterday for Pacer. Now, you can auto-sync Pacer with MFP to add your burnt calories to your diary.
I have my MFP set to sedentary, so the calories burnt walking will be fairly accurate for me.