Global Vegetation Index Products
The third generation polar Global Vegetation Index (GVI) products are used for monitoring the density and vigor of green vegetation. Useful applications of GVI products include classifying land cover, estimating crop acreage, and detecting plant stress.
The GVI products now online are weekly composites, and have a resolution of about 16 km. Also available are the Normalized Difference Vegetation Index, Fractional Vegetation, and the Precipitable Water Index products.
A comprehensive description of GVI products (my primary information source) can be found at the National Climatic Data Center's NOAA GVI Guide.