University of Idaho "Inside": http://inside.uidaho.edu/ -- Idaho's Geospatial Data Clearinghouse.
Idaho State University GIS Training & Research Center: http://giscenter.isu.edu/ -- Formed in 1998, the GIS TReC has grown into a respected research center focusing on land cover change in the semiarid savannas of the intermountain west.
ESRI Data Online: http://www.esri.com/data/find-data -- Ready-to-use maps and layers give more context and meaning to your data.
University of Idaho GAP Analysis: http://www.gap.uidaho.edu/ -- The Gap Analysis Program (GAP) at the University of Idaho (UI-GAP) has partnered with the U.S. Geological Survey Gap Analysis Program (USGS-GAP) for 25 years.
Interior Columbia Ecosystem Management Project (ICBEMP): http://www.icbemp.gov/spatial/ -- The Spatial Data section was developed to make spatial data available to interested parties.