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.
I think all the ones listed use GPS, so as long as you have GPS on and can get a fix then they should be pretty accurate considering the BB GPS can be used for turn-by-turn GPS navigation.
I think roadrunnergps is the best. its is pretty accurate in my opinion and the online site gives you pace and elevation in 30 second increments. can still listen to music while running also.