Graphical AltiMeter is the best GPS based altimeter for iPhone.

Features:
- Gorgeous Graph with Heights plotted for the last 24 hours;
- Zero Config, simple and easy to use, just open it and see your progress;
- Display the Height in meters or feet;
- Memorize all Heights every five seconds, so you can close the application and reopen it without problems;
- Portrait and Landscape orientations supported;
- Show local maximum and minimun height directly on the graph;
- Set the Height unit throught Settings application.

ATTENTION:
GPS altitude works only with the iPhone 3G and outdoors due to the GPS system technology.
Wrong Height may be caused by lacking or bad GPS signal and not by AltiMeter.
Don't forget to activate the "location" service in your iPhone settings.
AltiMeter prevent the locking of the iPhone, if you lock it the GPS signal will be lost.