This app was mentioned in 1 comment, with an average of 2.00 upvotes
Some great ones I've found:
Anchor alert - Excellent anchor watch software with SMS, and a really ingenious way of setting the anchor position:
MX Mariner - Offline activecaptain DB:
Windfinder Pro - The best wind measurement and forecasting app I've found:
Marinetraffic - 'net based AIS:
Pocketgrib - Handy grib downloader with offline viewing:
No affiliation with any of these, but I did link the "pro" or paid versions of each since we're a small community; anything to encourage more development!