ArcGIS Online - free base data, anywhere in the world! Don't have some base data? Just starting your GIS and only have a few layers? Working on a project outside of your regular area? For these and many other reasons you should be interested in ArcGIS Online. These are high-performance 2D and 3D web services and layerfiles for direct access by ArcMap, ArcGIS Explorer, ArcGlobe, ArcReader or ArcCatalog. These data services will continue to be enhanced and will be updated as new data become available - so you no longer have to worry about keeping your base data up to date!