If you want to have additional icons on a map, you can either make your own map or try to convince the maker of the map in question to add this feature. For the "official" OSM map (mapnik) the way to go would be file a ticket in trac and hope that the makers agree to your idea.
Please take into account that it is impossible to fulfill all requests, because this would clutter the map until it became useless. It is always necessary to choose some features out of all data (thereby omitting others).
answered 03 May '11, 17:41