Free Wyoming GIS Data

I do a lot of GIS work in Wyoming and have found that the there is a great amount of GIS data available for free.  The Wyoming Geographic Information Science Center is a great resource if you are looking for GIS data for the sate.  Their data services include the Wyoming Geolibrary where you can browse data sets by scale, theme, or project.  But the best way to download the data is from the WyGISC Data Server which allows you to interactively view and then clip the area that you are interested in and download the data.