How about it's GPS capabilities? Nautical chartplotting GPS. Or topographical mapping GPS. Those are pretty cool. Or a fish log that logs the spot, time, tide, and you can even attach a picture (taken with the phone) to the log of the hole on the river or the fish you caught.

There's some pretty cool stuff all in one device. Can even turn it into a universal remote to control any IR remote devices you may have. Never loose your remote again.

I just need the shockproof, submersible case now.
_________________________
. . . and God said unto them, Be fruitful, and multiply, and have dominion over the fish of the sea . . .