is there a running app for ipod nano 6th gen?

Ideally I'd like to start running but would like an app to cut in and say run or walk in intervals whilst playing my music. I didn't realise Nano doesn't have apps, I know there's a pedometer but I'm not much interested in that. Also I've heard there's a nike+ thing I can buy but would like to hear some feed back whether it's worth it. Thanks I appreciate any help or advice you can give