Colorado GIS
Everything you'd need for naming exit ramps, setting city names, and almost all road names.
Map View uses the ESRI GIS viewer and displays CDOT's recent GIS data (2010?).
Highway Data appears to use Navteq data for the base layer (tile graphics) with a CDOT GIS overlay for the numbered routes in Colorado.
Windshield is CDOT's own StreetView for all numbered routes in Colorado, this is especially useful for naming exit ramps.