The USGS National Mapping site - a perennially useful site for free basemap data

USGS Seamless Data Distribution System - offers free data downloads including user defined datasets, elevation point and profile tools, and more.

The Colorado Department of Transportation (CDOT) has a huge amount of free GIS data to download from their site, including highways, local roads, hydrography, and much more.

The GIS-T Symposium, Colorado Springs, Colorado The GIS in Transportation Symposium is sponsored by The American Association of State Highway and Transportation Officials, and offers the chance for transportation GIS professionals in government and industry to come together and learn from each other.

Topozone serves recreational and professional topographic map users.

GIS WWW Resource List A comprehensive list of Web servers of interest to the GIS community.

Odden's Bookmarks A meta-link! A link to at least 20,000 other cartographic links, with search capabilities.

GIS DataDepot A storehouse of a wide variety of GIS data, much of it free.

Geo Job Source Lots of other links on this page, to many professional organizations, and more.

National States Geographic Information Council The National States Geographic Information Council (NSGIC) is "an organization of States committed to efficient and effective government through the prudent adoption of geographic information technology".