Also some others- on an Iphone 4

WindAlert- shows wind speeds and directions from surrounding stations

AyeTides- tides from either nearest stations, or a place you pick.

BuoyData- wind speeds, etc form offshore buoys. Also has tide info

MyRadar- shows radar images across the nation, and lets you zoom to where you are too.

I also have Google Maps, which is kinda nice when you hit a port to show you where the nearest stuff is, like gas, or groceries.
It got me out of a jam once when I got behind a spoil bank in the ICW that the chart didn't show-The Google satellite image did .