Anyone know of a map service (WMS, WFS, Esri, other) for the US National Grid?
http://esri-flex.s3.amazonaws.com/flexviewer/index.html this site may be consuming a service but I don't know...
Have you tried the USNG on Google Map? http://dhost.info/usngweb/
You can also look at www.fgdc.gov/usng
If no web service is available, one option would be to host your own WFS/WMS service for the data for your internal use.