The maritime community work in yards and nautical miles. Neither of these units are supported in OpenLayers.
Their addition is a simple undertaking, through the extension of the OpenLayers.INCHES_PER_UNIT array to include the new types. A yard is 36 inches, and a nautical mile is 1852m (wikipedia.com).
Provision of these enumerated constants will allow them to be used as units in data files, and in the ScaleLine control being developed in my sandbox (http://dev.openlayers.org/sandbox/ianmayo/openlayers/examples/controls.html)
