Using Tile-based Map Services in Gaia 3.4
In Gaia 3.4 (due for release this week) two commercial mapping services are supported: Microsoft Bing Maps (formally known as Virtual Earth) and Yahoo! Maps. In addition, Gaia 3.4 supports the Tiles @ Home system from OpenStreetMap (http://wiki.openstreetmap.org/wiki/Tiles@home).
To use these maps in the free Gaia geospatial viewer all you have to do is select the map type (Roads, Aerial etc.) to generate a preview and enable the addition of the layer to the map. After adding the tile-service to the map you can change the map-type by right clicking on the layer name in the layers collection in the main application view (but remember only "Roads" maps are available from OpenStreetMap).
Notice that you may change the number of cached tiles - Remember that a lower amount of cached tiles will increase the number of Web service calls, while a higher value will increase memory consumption and thus the potential size of saved geospatial sessions (GSF).