[AugustH]

AyeTides already shows the stations sorted by their distance from you, in the Nearest view under Find. And, in v1.1 (to be sent to Apple tomorrow) you can eat your battery up by leaving the results of the search on the screen and AyeTides will continuously update the list.

And no, the Tide Graph program is a web application. There's no data on the iPhone. Lose your net connection, lose the tides.