Free NOAA Chart Downloads

Raster Nautical Charts (conventional charts) at:

http://www.charts.noaa.gov/RNCs/RNCs.shtml
Electronic Nautical Charts (new vector charts) at:

http://www.charts.noaa.gov/ENCs/ENCs.shtml
Booklet Charts (Experimental) (NOTE: BookletCharts are being updated every week with Notices to Mariners. Some errors are known to exist, e.g. the "Approximate Page Index" might not match the chart inside.):

http://www.nauticalcharts.noaa.gov/staff/BookletChart.html
United States Coast Pilot. The United States Coast Pilot® consists of a series of nautical books that cover a variety of information important to navigators of coastal and intracoastal waters and the Great Lakes. Issued in nine volumes, they contain supplemental information that is difficult to portray on a nautical chart. :

http://www.nauticalcharts.noaa.gov/nsd/cpdownload.htm
A good program for viewing the charts and USB connection of GPS:

http://opencpn.org/