ESRI's Geoportal is an open-source metadata catalog system capable of providing an OGC CSW Service. Due to its good documentation and relatively easy workflow for handling custom metadata profiles, USGIN has adopted Geoportal as its primary catalog system.
An ESRI Map Service is the standard web service provided by ArcGIS Server. While relatively easy to create, there are a number of important options to consider when implementing such a service.
A Map Service is the standard web service provided by ArcGIS Server. These services can be produced by simply "publishing" an ArcMap document (.mxd) to an active ArcGIS Server. Benefits of using ESRI Map Services include utilization of the rich cartographic capabilities of the ArcGIS Desktop environment, relatively simply production, native integration with other ArcGIS Desktop products, and a rich and well-documented set of APIs for providing services in web applications.
Although this services are quite easy to produce, there are a number of important things to consider during the production process. More information about building ESRI Map Services can be found on this website as well as through ESRI's help documents.
ESRI's ArcExplorer is a lightweight, no-cost GIS data viewer. Note that the .NET version of ArcExplorer is significantly different from the Java edition.
ArcGIS Server is ESRI's network- and webservice-centric GIS application suite. Among other, ArcGIS Server offers WMS, WFS, WFS-T, WCS, and KML service capability as well as web application SDKs for JavaScript, Flex, Silverlight, .Net, and Java.
USGIN metadata can now be searched through ESRI's GEO Portal (http://geoss.esri.com) and GEOSS GEO Viewer (http://geoss.esri.com/geoviewer) portals. On the search tab or window select "US GIN" under "Search In" to look for USGIN specific resources.
This is still a work in progress and many kinks have to be worked out. However, we are excited about our ESRI partners' contributions.