Manifold System GIS

A U.S. based company, publishes Manifold® System, add-ins for Microsoft's Access® data base, data sets, utilities and other data visualization and analysis software, including user friendly GIS software. Manifold is a relatively inexpensive GIS option.

There is a helpful article by Arthur J. Lembo Jr. comparing common tasks in Manifold and ArcGIS  here. (Via the AnyGeo blog)