The US National Park Service pictograph set might be a good candidate set as these are widely used on maps and in the text of guidebooks, etc. - as well as in GIS applications.
http://www.nps.gov/hfc/carto/map-symbols.cfm http://commons.wikimedia.org/wiki/File:MapSymbols_other_US_NPS.svg http://commons.wikimedia.org/wiki/File:Map_symbols_US_NPS.svg These symbols also have been placed in the public domain - so there should be no copyright issues. This set of symbols, has been around since 1974 and is now well established. It is somewhat curious that they haven't already found their way into the Unicode Standard as in general they seem more useful than many other symbols which have been encoded. http://www.thesmartset.com/article/article07140901.aspx - Chris
