I used that URL in the "Add Content > GIS Service" search box with ArcGIS Explorer Online. But it gives zero results. Can someone tell me if WMS services can be viewed in AGXO? If yes, how to find them?
Sorry but Explorer Online doesn't currently support adding WMS services. It is, however, something we're considering for a future release. You might want to post this idea to the new "Ideas" site...that way other users can vote on it too.