If you have an Android or iPhone, your are getting a late Christmas present from the makers of the RunKeeper App. It’s FREE to download in the month of January. Up until now there as been a scaled down free version and a fee based Pro version. Both are now free for the taking. You can find both in the app store for each phone.
I use RunKeeper and have really liked it. The free version can be a little inaccurate on the mileage at times, but the rest of the application works great. It will also auto tweet right to Twitter for ya!
The Pro Version comes with audio cues, customized interval workouts, integrated RunKeeper FitnessClasses and best of all…NO ADS!
There is more info on RunKeeper at http://runkeeper.com