I've found some great apps for my iPhone I thought I'd mention here that can be a great thing to have on board. I'm interested in what others have in this regard. Here goes :

PREDICTWIND : wind forcaster and planner for even multi day trips. Probably my fav app.

WIND ALERT: a nice complimentary app to PREFICTWIND. Not as good but still fantastic and is good to have when considering a PW  forecast.

MARINE TRAFFIC: this is an AWESOME app that gives real time position of every ship out there that's track able. Particularly good for monitoring commercial traffic.

CHARTS by EarthNC: the name is drab but the app is a brilliantly done mapping tool that can trace your plotted course on NOAA maps outdone only by:

BOAT TRACKER: uses sat imagery with a rainbow spectrum of color to calibrate speed in a quick visual that computes the color once the trip is over and max and minimum speeds can be    arrived at for color coding. Its a blast to see your speed run in bright red and your slow pace in blue or turquoise.  This is a fantastic app. Gives trip averages, etc etc.

BOUY DATA: my fav bouy app gives all the pertinent info you'd want most if the time. I like to have this to check the source other apps use to generate maps of trends and patterns. Again a great app.

Lastly: WHATKNOT- a simple but effective instructional app on making sailing related knots.

my most treasured top two apps are :

BOAT TRACKER and PREDICT WIND. MARINE TRAFFIC is next.

Pete

ps: it helps to have the add on battery pack for BOATTRACKER as it'll use too much battery and be dead in four hours if u don't. For a hundred bux or less u can double it - for another hundred u can triple .