I think GPSLogger from emacberry is an excellent app for fitness tracking. If you put it in "Timing View," you will have a screen showing your speed and distance as well as a decent amount of detailed GPS data. In this mode it can also be set to give you an audio indication of specified distance intervals (ie: beep every mile or km).
Cool app, free, and the log files are uploadable to Google Earth so you can see exactly where you went. The other aspect I like is that if you're a trail runner or mountain biker and go to places that don't have cell coverage, the app still works/runs as intended so long as you have a GPS lock.
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