<URL:http://wwwdaac.msfc.nasa.gov>
  Marshall Space Flight Center Distributed Active Archive Center (MSFC.DAAC).
Data holdings are primarily aimed at researchers investigating facets of the hydrologic cycle.  Available data includes SSM/I NOAA/NASA Pathfinder Products, TOVS NOAA/NASA Pathfinder Path C1 Products, SSM/I Antenna Temperatures and Sensor Counts, and Climatological Summaries.

<URL:http://www-nsidc.colorado.edu/NASA/GUIDE/>
  The National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) maintains information about snow cover and avalanches, glaciers and ice sheets, floating ice, ground ice and permafrost, atmospheric ice, extra-terrestrial ices, paleoglaciology and ice cores.   Also see the NSIDC home page at <URL:http://www-nsidc.colorado.edu/>.

<URL:http://www.nohrsc.nws.gov>
<URL:gopher://gopher.nohrsc.nws.gov>
<URL:ftp://ftp.nohrsc.nws.gov/pub>
  National Operational Hydrologic Remote Sensing Center.  Snow cover 
measurements in US and Canada, and snow water equivalent data.

<URL:http://polar.wwb.noaa.gov/seaice/>
  The National Centers for Environmental Prediction (NCEP) Sea Ice home page.
Contents include the most recent automated sea ice analysis for both
hemispheres and ice drift forecast guidance.

<URL:http://www.dow.on.doe.ca/ice/home.ice.html>
  Ice Services Branch of Environment Canada.  Information about available products and services, and some sample data.

<URL:ftp://meds02.met.fu-berlin.de/pub/SEA-ICE/>
  The Institute for Meteorology of the Free Uni Berlin provides
operation sea-ice maps.  Text is mostly in German but there are some
English translations.

<URL:http://www.meto.umd.edu/~alan/soil_moisture/>
  University of Maryland Global Soil Moisture Data Bank.  A collection
of data, model output, and links to soil moisture information.