NITF for ArcGIS® Desktop versions

Free

ArcGIS Explorer Desktop is a GIS viewer that gives you an easy way to explore.

ArcGIS Engine is a complete library of embeddable GIS components for developers.

Free

It expands the geodatabase functionality of the ArcGIS Explorer Desktop app.

Free

It adds projections and geotransformations for use with ArcGIS Explorer Desktop.

Free

You can view an image service using various client applications.