Surfline (free):
Get a comprehensive five-day forecast that includes surf heights, wind speeds, tides, and more for thousands of breaks worldwide. A premium membership ($13/month) also offers ad-free live streaming HD surf cams.
Surfr (free):
Facebook meets Yelp meets the surfing world. Create a profile, chronicle your adventures, and share photos with members of this online community. You can also tag a location with a social good category (i.e. clean water or medical supplies), and the app will crowdsource user feeds to determine issues and help find solutions.
NOAA Ocean Buoys ($1.99):
Has the surf cleaned up? Has the swell arrived? This app from the ocean-focused federal agency answers those questions, and provides detailed information on wave periods, air temps, and more.