Also available at Kansas State University . The official list by the United State Department of Agriculture. Range grass information by the Texas Natural Resource Web. Images of Poaceae , Gerald D. Carr, University of Hawaii. Nice images of a few grasses.
Site is frequently down.
Interactive plant identification , List of programs compiled by M. J. Dallwitz. Internet Directory for Botany Web Page Find botanical gardens, addresses of biologists, images, journals, etc. Missouri Botanical Garden Research International links to botany around the world and W3 Tropicos which provides a nomenclatural database and associated authority files. And if you want to peek just at the grass genera, here's the link. Northern Prairie Wildlife Research Center US Geological Survey compendia on biological resources of a region.