I am loving Buddy Runner - an application which works on a Google android phone which I am luck enough to have. It really keeps me motivated to walk. It calculates my calorie expenditure and even takes into account the increases and decreases in calorie expenditure according to elevation as it picks up a GPS signal. All the info is sent to a dashboard which keeps a record of all my walks, including maps and pace etc. There are other apps out there that work with other smartphones including iphones, but I particularly like this one. I also like MyTracks, but it doesn't count calories.