A blank map of Colorado, outlining the counties, as of 2005. This map uses azimuthal equidistant projection, centered on (-105.7167, 39.1333) (degrees longitude, latitude).  The area outside Colorado is transparent, so it should look nice on non-white backgrounds.
The data I used is apparently accurate to 0.000278 degrees, or about 100 feet.  The coordinates in this map are in meters.

This map is probably not eligible for copyright.  Just in case, I release my own contributions to the public domain.
Own work using: nationalatlas.gov, specifically countyp020.tar.gz.  I used shpdump to extract the Shapefile.  See the talk page for more details.
David Benbennick