Right now I use my iPhone to track how far I'm walking etc, but I wouldn't mind an easier way to track distance, and more really, and most especially when I can't carry my phone on my body. I like both of these for different reasons, but I think I might prefer the top one. Though what I'd really like something that has a watch and links up to my phone too, oh and can pay for things, so I can just leave my wallet behind, so maybe waiting awhile might be the answer.
The Withings Pulse O2 is tracks steps, elevation, calories burned, distance traveled, monitors your sleep and can even check your heart rate and blood oxygen level all in 1 little package. it syncs to both iOS and Android with it's App and can link up to RunKeeper and MapMyFitness. The unit comes in blue or black and can be worn on your wrist or with a clip. A optional color pack of clips lets you customize your clips a bit more. You can even just drop it into your pocket or bag. The unit sells for $119, which is a good price for such a great range of options. See more on the Withings site.
This one's a bit pricier, but it offers a year long run on it's battery life, so no charging every few days. This vívofit learns your daily activity levels and assigns goal that are adjusted as you meet them. It monitors steps, calories, distance and monitors sleep in a water resistant band, so you can wear it all day, every day from bed to shower to out and about. The built in motivators will help you get moving and stay moving. There is an optional heart rate monitor as well. This one runs $129.99 or $169.99 with the heart rate monitor. More details on the Garmin site.