http://nsidc.org/data/seaice/passive microwave concentration, extent, velocity, melt onset, brightness temperature, etc.

visible and infrared sea ice extent, melt ponds, velocity, etc.

sea ice charts, sea ice drift and velocity, sea ice concentration and extent, sea ice thickness, sea ice age, and others from ships, buoys, upward-looking sonar, manned research stations, etc.

http://www-radar.jpl.nasa.gov/rgps/

high-resolutionsea ice motion,deformation,age,and thickness

Sea ice temperature and albedo from AVHRR, MODIS, and TOVS:http://www-nsidc.colorado.edu/data/nsidc-0069.htmlhttp://modis-snow-ice.gsfc.nasa.gov/sea.html

Twice-yearly (spring-fall) ice thickness and roughness from ICESat - http://nsidc.org/data/icesat/

Ice thickness is also available from ERS-1, ERS-2, and ENVISAT

Upcoming satellite missions:

Cryosat-2 ICESat-IISAR altimeterLaser altimeterplanned launch in late 2009 launch in ~2015