Here are a few "regional links," and a few "super links" to be enjoyed by marine and nautical enthusiasts:

Chesapeake Bay.   
http://www.thechesapeakebay.com/
Great information for Chesapeake Boaters

Weather
http://www.nws.noaa.gov/om/marine/forecast.htm
http://www.ndbc.noaa.gov/
Marine Text and National Data Buoy Center

Boats For Sale Search Engines
http://www.yachtworld.com/
YachtWorld

U.S. Coast Guard--Office of Boating Safety.
http://www.uscgboating.org/
Very good information and many "best" boating sites.

Mark Rosenstein's Sailing Page.
http://www.apparent-wind.com/sailing-page.html
Great links to a wide variety of maritime and nautical sites.

The Mother of all Maritime Links.
http://boat-links.com/boatlink.html
More excellent links.  Enjoy.

The Society of Accredited Marine Surveyors
http://www.marinesurvey.org

American Boat and Yacht Council
http://www.abycinc.org