navizon works for me.. they disabled the cell radio side of it, so if you have your wifi switch off, then it's just keeping the gps on.. you can also tell it how often to update the location..***EDIT**this is for location tracking in full version, or required if on free *I think...******* 10-15sec default..
it "requires" ***\/\/\/\/\/**** an internet connection but for this purpose you should be fine.
***EDIT**
new beta available that re-enables cdma, works well, count seems accurate for cells, out of beta soon I hope...

also in the beta they say the requirement for a data connection on gps enabled devices is no longer required ***********